International Journal of Renewable Energy Technology (13 papers in press)
Short term solar energy forecasting using GNN integrated Wavelet based approach
by Priyanka Chaudhary, Mohammad Rizwan
Abstract: The power generation from solar energy is gaining more attention because of advancement in the solar photovoltaic technology including enhanced efficiency of solar cells by incorporating the good materials. In the present scenario the bidding of power is done on 15 minutes basis by many distribution companies. Keeping in mind aforesaid, 15 minutes ahead short term solar energy forecasting has been done and presented. As the power from solar energy is fluctuating and nonlinear in nature, the results obtained from mathematical models are not found satisfactory. Therefore, an intelligent approach based on wavelet transform and generalized neural network (GNN) is developed and applied for the short term solar energy forecasting problem. The results obtained from the proposed model are evaluated on the basis of statistical indicators like root mean square error (RMSE) and mean absolute error (MAE). It is concluded that the performance of the proposed model is found better as compared to GNN model.
Keywords: Generalized neural network; wavelet transform; grid integrated solar PV systems; solar energy forecasting.
Empirical model for prediction of density and water resistance of corn cob briquettes
by Simeon Jekayinfa, Ralf Pecenka, Ifeolu Orisaleye
Abstract: Biomass obtained from agricultural wastes have a high potential for energy generation, particularly in developing countries. The poor properties of the agricultural biomass cause handling problems and limit the suitability as fuel in conventional grates. Densification of biomass into briquettes enhances its fuel properties. In this study, effects of pressure (9, 15 MPa), temperature (90, 120
Keywords: Biomass briquette; densification variable; corn cob; empirical model; density; water resistance.
Modelling and analysis of solar dryer cum water heater through CFD and analytical methods
by Subramaniam Senthilkumar, M. Natarajan, S. Duraikumar
Abstract: Active utilisation of solar energy for heating and drying is need of the day for several domestic and commercial applications. Modelling and analysis of a typical solar crop dryer cum water heater has been presented in this paper. A thin layered bed solar dryer with water heater was modelled in solid works software. CFD analysis is carried out to evaluate thermal and air flow performance. A performance analysis by analytical modelling was conceded by energy balance equations for working fluids and solar dryer components. The results of analytical method and CFD analysis were associated. The optimum performance parameters of the system were arrived with varied flow rate data.
Keywords: modelling; simulation; CFD; performance analysis; solar energy; solar dryer; water heater; analytical method; energy balance; flow rate; velocity profile.
Predictive control of variable speed wind energy conversion chain-based multilevel converters with balanced voltages
by Zakaria Lammouchi, Said Chikha, Kamel Barra
Abstract: The paper presents an improved predictive rotor current control of variable speed wind energy conversion system based doubly fed induction generator. The method is based on finite states space model of the converter. The proposed control selects the optimal switching state that minimises the error between orthogonal rotor current components predictions to their computed values. Then, the optimal voltage is applied to the output of the power converter. Once the proposed predictive strategy is validated, multilevel converters, well suited for high power-medium voltage application are used to improve and highlight the obtained results in term of low ripples, high efficiency and low harmonics. One of the most benefits of the proposed control is its flexibility, so more terms can be added in the cost function to satisfy multiple objectives simultaneously. The superiority of the proposed predictive control over the conventional control will be investigated and confirmed by simulation results.
Keywords: variable speed wind energy conversion system; predictive rotor current control; cost function; multilevel converter; unbalance voltage.
Special Issue on: ECRES2017 Advances in Renewable Energy Systems
The effect of non-uniformities in temperature on the performance parameters of an isolated cell photovoltaic module with a compound parabolic concentrator
by Damasen Ikwaba Paul, Mervyn Smyth, Aggelos Zacharopoulos
Abstract: This study investigated the effect of non-uniformities in cell temperature on the open-circuit voltage, short-circuit current, maximum power output and fill factor of each cell in a PV module with 11 isolated cells placed in a compound parabolic concentrator (CPC). To achieve this objective, symmetric CPC and a photovoltaic (PV) module were designed and fabricated. The PV module with and without the CPC were both exposed to a constant solar illumination of 615 W/m2 continuous for 18 minutes. It was found that the temperature for the cells in the PV module without the CPC were almost constant while that with the CPC varied by 20%. Due to non-uniformities in cell temperature, the decrease in open-circuit voltage, maximum power output and fill factor was higher for cells with higher temperature than similar cells with lower temperature. However, the short-circuit current slightly increased with cell temperature.
Keywords: non-uniformity in temperature; cell temperature; temperature coefficient; energy flux distribution; isolated cell PV module; compound parabolic concentrator; CPC; temperature coefficient of the short-circuit current; temperature coefficient of the open-circuit voltage; temperature coefficient of the maximum power output; temperature coefficient of the fill factor.
Optimal placement and sizing of DSTATCOM using firefly algorithm in the distribution system
by K. Padmavathi, K. Rama Sudha
Abstract: The electric power distribution system must be intended to operate and deliver acceptable level of electrical energy to consumers. Distribution static compensator (DSTATCOM) is a custom power device implemented in the distribution system to improve the power quality. This paper presents the optimal size and placement of DSTATCOM in the distribution system by using firefly algorithm (FA). Minimisation of power loss and minimisation of installation cost of DSTATCOM are considered as the objective function (OF), where the voltage and current limits of the buses are chosen as the optimisation constraints. The performance of the proposed methodology using FA is demonstrated on IEEE 33-bus and 69-bus radial distribution systems using MATLAB software. Backward/forward sweep algorithm is used for load flow analysis of radial distribution system. The efficacy of the proposed methodology using FA is compared with the results obtained by using immune algorithm (IA).
Keywords: backward/forward load flow; DSTATCOM; radial distribution system; firefly algorithm; FA; power quality; voltage source converter; VSC.
Analysis of a heat pump assisted solar water heating system using TRNSYS program
by Salih Coşkun, Gamze Kandirmiş, Cüneyt Tunçkal
Abstract: Traditional solar hot water system (SDHW) is an important system for the use of renewable energy sources. In this system, while water is heated by sun in summer or hot days, it is heated by electric heaters in winter, or cold days. So efficiency of this system is low in winter because of very high electric consumption. This problem can be solved using heat pump instead of electric heaters. In this study, a heat pump assisted solar domestic hot water system (HP_SDHW) was designed to increase efficiency. Both systems were modelled and simulated depending on time using (TRNSYS) program. An analysis was performed through the year for both systems at SARAJEVO/ Bosnia and Herzegovina conditions. As a result of the annual analysis, it was found that the HP_SDHW system consumes approximately 40% less electricity than the traditional SDHW system. The solar fraction of the HP_SDHW (%67) was found higher than the SDHW system (%46).
Keywords: heat pump; solar energy; renewable energy; transient system simulation; TRNSYS; simulation; domestic hot water; DHW.
General situation of wind energy source in Turkey and wind turbine technologies
by Yusuf Alper Kaplan, Sener Agalar, Hasan Bildircin
Abstract: The increasing need for new energy sources is a result of the rapidly increasing global population and consumption of fossil fuels. In order to achieve more efficient use of wind energy in Turkey, the establishment of more efficient wind turbines with new technologies and the widespread use of wind-generating systems are inevitable. The regional distribution of the wind energy potential of Turkey, the regional and general usage rates and the policies followed in wind energy subjects are worth investigating. Besides, it is very important to discover new wind fields, to calculate the capacities of these areas by technical analysis methods and finally to use them. Recently, wind power capacity has increased dramatically in Turkey and accompanying that, the wind turbines that produce it have become more affordable and more efficient for wind energy producers. Wind turbine technologies have been mentioned in general and generator models used in wind turbines have been examined. Consequently, wind energy resource is not efficiently used in Turkey and how the using of wind energy potential is improved is generally discussed.
Keywords: DFIG; energy policy; energy structure; PMSG; renewable energy; wind energy; wind turbine generator; Turkey.
Theoretical and experimental analysis of glazed serpentine tube flat plate collector for effluent evaporation
by Deepak C. Sonawane, Vinod B. Tungikar
Abstract: In this paper theoretical and experimental study of serpentine tube flat plate collector for evaporation of water in the effluent is presented. The performance of the flat plate collector depends on various factors including the collector construction and the arrangement of the system. The prototype working model has been fabricated to prove the feasibility and viability of the evaporation system. Results obtained show that the evaporation rate of water in the effluent increases, with the increase in solar radiation, wind velocity and decrease in mass flow rate of effluent, relative humidity and concentration of the effluent. The evaporation rate of effluent in the single cover serpentine tube flat plate collector is found to increase by 41 % compared to the solar pan and 16% to the single cover FRP flat plate collector.
Keywords: solar energy; effluent; evaporation; glazing; serpentine tube flat plate collector.
Power electronic converters without electrolytic capacitors
by Alex P.M. Van Den Bossche, Salim Haddad, Mourad Mordjaoui
Abstract: Power electronic converters may have a quite long lifetime, but some applications such as converters for automotive and photovoltaic could even desire a longer life. One of the elements to increase the lifetime of converters is to avoid electrolytic capacitors. They can be replaced by metalised film capacitors or ceramic capacitors. A lot of converter types can be re-designed to use them, but it influences the way of designing, as a lower capacitance value is used. Electrolytic capacitors are one of the elements that reduce the lifetime of power electronic converters gradually an adapted design can avoid that electrolytic capacitors have to be used in converters. A range of examples can be shown from fractions of watts up to Gigawatt. The purpose is to give an overview of topologies, not to discussing them in detail: for example gate drive circuits, single and three-phase converters where film capacitors are used in the DC link and high voltage DC converters. These techniques are useful to prolong the life of converters and to allow higher ambient temperatures, typical application domains are PV and other grid connected converters, converters for battery charging and general electric vehicle applications.
Keywords: power electronic converters; electrolytic capacitors; lifetime.
Design and implementation of a prototype hybrid micro grid model for available weather conditions
by Srishti Singh, Prerna Gaur, Madhur Kapoor, Sankalp Goel, Satinderpal Singh, Sonali Negi
Abstract: The increasing threat to environment and the consequent depletion of renewable energy resources has led the hybrid energy system to come in the forefront. A renewable energy model (PV-wind hybrid integration) is complementary in nature and can potentially address the energy crisis in the fast developing society. A MATLAB/SIMULINK based PV-wind hybrid generation system is developed. The proposed work is aimed at to design and simulate a hybrid model according to the power needs of a test area consisting of around thirty households with 4 kWh/day average household requirement. The simulated study is cross verified with the similar hardware prototype to check feasibility, sustainability and viability of the hybrid model. The weather conditions consisting of insolation, day, time, temperature, latitude, longitude, panel angle, etc. of the test area have been acquired for hardware purpose. A case study of a state in India is used to develop the proposed model.
Keywords: renewable energy; micro-grid; PV-wind hybrid; Simulink; maximum power point tracking; Perturb and observe; genetic algorithm; SEIG; WTIG.
Bioethanol production from sawdust of Colombian pine: conditions and efficiency
by Rodrigo Andrés Sarria-Villa, José Antonio Gallo-Corredor, Martha Isabel Páez, Ricardo Benitez-Benitez
Abstract: The growing importance of the transport sector in relation to energy demand underscores the need for action to improve energy efficiency and to develop economically and environmentally viable energy alternatives. This paper presents the results of the conditions under which ethanol can be obtained from the sawdust of the forest species Pinus patula and Pinus oocarpa, which were grown in the Cauca Department in Colombia. Highest percentages of cellulose were with 12% of NaOH. Enzymatic hydrolysis with the fungus Trichoderma viride led to cellobiose and glucose for P. patula and P. oocarpa between 7% and 37% respectively. A fermentation process using Saccharomyces cerevisiae at 18 h allowed obtain yields of 100% and 96.85% of ethanol to samples of Pinus patula and Pinus oocarpa respectively. These results indicate the feasibility of the pretreatment, hydrolysis and fermentation of the studied pine species to obtain ethanol from sawdust.
Keywords: sawdust; gas chromatography; hydrolysis; ethanol; HPLC; pine.
Special Issue on: Sustainable Energy Technologies
STUDIES ON HYDROGEN FUELLED STATIONARY C. I. ENGINE OPERATED END-UTILITY SYSTEM
by Vinod Singh Yadav, Dilip Sharma, S.L. Soni
Abstract: The refineries turned in a better performance with their cumulative 181 million tones crude throughput, almost 7 per cent more than the previous fiscals achievement and a little over 2 percent of the planned target. The world is presently confronted with the twin crisis of fossil fuel depletion and environmental degradation. Combined residential and commercial energy demand is expected to increase in order to meet the expected increase in electricity demand as the worlds population shall grow and more people shall move to urban areas with access to electricity. The search for an alternative fuel, which promises a pleasant link with sustainable development, energy conservation, management, efficiency, and environmental safeguarding, has become highly noticeable in the present context. rnIn this investigation, fresh air with hydrogen enrichment was used as intake charge in a C. I. engine. Experiments were conducted on a 1-C, 4-S, air-cooled, stationary direct-injection diesel engine (Kirlosker TAF1) with maximum 1500 rpm and maximum 4.4 kW capacity coupled to an electrical generator. The injection timing (17
Keywords: Hydrogen-Enrichment; Injection timing; Flow rate of hydrogen; Performance.