Renewable Energy System

Nowadays, in many countries the increase of generating capacity takes place in small units of so-called distributed generation (DG), and among them in hybrid power (generating) systems (HPS). They use primary energy conventional sources as well as renewable energy sources (RES), and in many cases produce electricity and heat (CHP). It is very often that definition of distributed generation is connected with definition of renewable energy sources. Using of renewable energy sources is one of the crucial components of the sustainable development, giving rationale economic, ecological and social effects. Support for development of renewable energy sources utilization became very important objective within the European Union.

The Chilean government has determined that a renewable energy quota of up to 10% of the electrical energy generated must be met by 2024. This plan has already sparked interest in wind, geothermal, hydro and biomass power plants in order to introduce renewable energy systems to the country. Solar energy is being considered only for demonstration, small-scale CSP plants and for domestic water heating applications. This apparent lack of interest in solar energy is partly due to the absence of a valid solar energy database, adequate for energy system simulation and planning activities. One of the available solar radiation databases is 20–40 years old, with measurements taken by pyranographs and Campbell–Stokes devices. A second database from the Chilean Meteorological Service is composed by pyranometer readings, sparsely distributed along the country and available from 1988, with a number of these stations operating intermittently. The Chilean government through its National Energy Commission (CNE) has contracted the formulation of a simulation model and also the deployment of network of measurement stations in northern Chile. Recent efforts by the authors have resulted in a preliminary assessment by satellite image processing. Here, we compare the existing databases of solar radiation in Chile. Monthly mean solar energy maps are created from ground measurements and satellite estimations and compared. It is found that significant deviation exists between sources, and that all ground-station measurements display unknown uncertainty levels, thus highlighting the need for a proper, country-wide long-term resource assessment initiative. However, the solar energy levels throughout the country can be considered as high, and it is thought that they are adequate for energy planning activities – although not yet for proper power plant design and dimensioning.

This paper presents the design, construction and results of a solar powered incubator and pools for rearing yaca& a specie of the crocodile family, found in notthern Argentina. The desgin was developed by the Research Centre Habitat 8c Energy, Faculty of Architecture, Design and Urbanism, Buenos Aires University in the framework of a Cooperation Agreement with the Argentine Wild Life Foundation. The installation, located in a Wild Life Refuge in a remote subtropical area of the Chaco Province in the northeast region of Argentina, consists of an incubation chamber for hatching the yacark with strict temperature conditions, pools for rearing the young during a year, heated by solar energy, an auxiliary wood-tired water heater and PV system to power the pumps control system and other minimal requirements such as lighting. The concepts, system development and integration, construction process and measured performance am presented together with the fti results of this project which integrates low impact renewable energy systems to support the conservation of an endangered specie. IQ I998 Published by Elsevier Science Ltd. All rights reserved.

Energy is a vital input for social and economic development. As a result of the generalization of agricultural, industrial and domestic activities the demand for energy has increased remarkably, especially in emergent countries. This has meant rapid grower in the level of greenhouse gas emissions and the increase in fuel prices, which are the main driving forces behind efforts to utilize renewable energy sources more effectively, i.e. energy which comes from natural resources and is also naturally replenished. Despite the obvious advantages of renewable energy, it presents important drawbacks, such as the discontinuity of generation, as most renewable energy resources depend on the climate, which is why their use requires complex design, planning and control optimization methods. Fortunately, the continuous advances in computer hardware and software are allowing researchers to deal with these optimization problems using computational resources, as can be seen in the large number of optimization methods that have been applied to the renewable and sustainable energy field. This paper presents a review of the current state of the art in computational optimization methods applied to renewable and sustainable energy, offering a clear vision of the lastest research advances in this field.

This paper concerns on modeling of stand alone biomass and solar energy system in Sarawak. Sarawak state needs to develop a number of small power generations in remote areas using stand alone system. Stand alone power systems are of special interest combined with renewable energy design in areas not connected to the capital electric grid. The ultimate goal of this project is to obtain a reliable autonomous system with the optimization of the components size and the improvement of capital cost. Simulated model for photovoltaic system is designed using MATLAB Simulink together with PSIM and model for biomass is designed using HoneyWell software to investigate the design and the performance of stand-alone renewable energy systems. Furthermore, the Hybrid Optimization Model for Electric Renewable (HOMER) software is important to develop the cost optimization analysis. The costs for both renewable systems are optimized, compared and analyzed. For a particular scenario, inputs to HOMER include load data, renewable resource data, system component specifications and costs, and a variety of information of optimization, such as number of components in order to obtain the best possible system for rural areas.

Nowadays, different power generation strategies for grid-connected systems can be found, ranging from single high power plants (tens and hundreds of MW), to thousands of small wattage (below 1 kW) microgenerators. This paper studies a new power topology for the latter, based on a bidirectional Flyback converter. The comparison with the standard topology for this kind of converters is carried out, and the constraints for the control scheme are also studied.

A renewable energy system RES with cooperation of diesel driven autonomous doubly fed induction generator is presented in the paper. The analysis takes into consideration the power system, where the main power source is a variable speed diesel engine, which operates in full range of power consumption. The RES source is used for diesel engine fuel reduction. The paper presents power distribution between the two sources during supply of isolated load. Reduction of fuel consumption by the use of variable speed operation of diesel engine is also discussed. The issue of energy storage ESt cooperation with RES-Diesel power generation system is evaluated. Simulation results of described system are obtained using PSIM simulation software and they are presented in the paper.

Using life cycle assessment, metrics for calculation of the input energy requirements and greenhouse gas emissions from utility scale energy storage systems have been developed and applied to three storage technologies: pumped hydro storage (PHS), compressed air energy storage (CAES) and advanced battery energy storage (BES) using vanadium and sodium polysulphide electrolytes. In general, the use of energy storage with electricity generation increases the input energy required to produce electricity, as well as the total greenhouse gas emissions. Despite this increase, the life cycle GHG emission rate from storage systems when coupled with nuclear or renewable sources is substantially lower than from fossil fuel derived electricity sources. GHG emissions from PHS when coupled with nuclear and renewable energy systems are lower than those from BES or CAES. When coupled with fossil generation, CAES has significantly lower net GHG emissions than PHS or BES.

A real-time system for protecting and monitoring a DC/AC converter has been designed and constructed. The proposed system consists of (a) a hardware protection unit for fast reaction, load protection and inverter fail-safe operation and (b) a microcontroller unit for calculating critical parameters of the inverter operation. The control unit malfunctions have not been investigated in this study. The proposed hardware architecture and sensors form a low-cost and reliable control unit. The experimental results show that the proposed system ensures the inverter protection and fail-safe features. The proposed unit can be used to increase the reliability of any power inverter in AC motor drives, renewable energy systems, etc. or can be incorporated in any UPS system.

An integrated renewable energy (RE) system for powering remote communication stations and based on hydrogen is described. The system is based on the production of hydrogen by electrolysis whereby the electricity is generated by a 10 kW wind turbine (WT) and 1 kW photovoltaic (PV) array. When available, the excess power from the RE sources is used to produce and store hydrogen. When not enough energy is produced from the RE sources, the electricity is then regenerated from the stored hydrogen via a 5 kW proton exchange membrane fuel cell system. Overview results on the performances of the WT, PV, and fuel cells system are presented. #

Greenhouse gas mitigation strategies are generally considered costly with world leaders often engaging in debate concerning the costs of mitigation and the distribution of these costs between different countries. In this paper, the analyses and results of the design of a 100% renewable energy system by the year 2050 are presented for a complete energy system including transport. Two short-term transition target years in the process towards this goal are analysed for 2015 and 2030. The energy systems are analysed and designed with hour-by-hour energy system analyses. The analyses reveal that implementing energy savings, renewable energy and more efficient conversion technologies can have positive socio-economic effects, create employment and potentially lead to large earnings on exports. If externalities such as health effects are included, even more benefits can be expected. 100% Renewable energy systems will be technically possible in the future, and may even be economically beneficial compared to the business-as-usual energy system. Hence, the current debate between leaders should reflect a combination of these two main challenges.

In this paper, the performance of wind energy system is assessed thermodynamically, from resource and technology perspectives. The thermodynamic characteristics of wind through energy and exergy analyses are considered and both energetic and exergetic efficiencies are studied. Wind speed is affected by air temperature and pressure and has a subsequent effect on wind turbine performance based on wind reference temperature and Bernoulli's equation. VESTAS V52 wind turbine is selected for (Sharjah/UAE). Energy and exergy efficiency equations for wind energy systems are further developed for practical applications. The results show that there are noticeable differences between energy and exergy efficiencies and that exergetic efficiency reflects the right/actual performance. Finally, exergy analysis has been proven to be the right tool used in design, simulation, and performance evaluation of all renewable energy systems.

Public awareness of the need to reduce global warming and the significant increase in the prices of conventional energy sources have encouraged many countries to provide new energy policies that promote the renewable energy applications. Such renewable energy sources like wind, solar, hydro based energies, etc. are environment friendly and have potential to be more widely used. Combining these renewable energy sources with back-up units to form a hybrid system can provide a more economic, environment friendly and reliable supply of electricity in all load demand conditions compared to single-use of such systems. One of the most important issues in this type of hybrid system is to optimally size the hybrid system components as sufficient enough to meet all load requirements with possible minimum investment and operating costs. There are many studies about the optimization and sizing of hybrid renewable energy systems since the recent popular utilization of renewable energy sources. In this concept, this paper provides a detailed analysis of such optimum sizing approaches in the literature that can make significant contributions to wider renewable energy penetration by enhancing the system applicability in terms of economy.

A direct phase model of synchronous machines implemented in MATLAB/SIMULINK is presented. The effects of the machine saturation have been included. Simulation studies are performed under various conditions. It has been demonstrated that the MATLAB/SIMULINK is an effective tool to study the complex synchronous machine and the implemented model could be used for studies of various applications of synchronous machines including in renewable and DG generation systems.

In the past few decades, the energy paradigms in many countries are experiencing significant change from fossilbased resources to cleaner renewables. It is expected that the scenario of highly penetrated renewables is going to be further enhanced. This requires that the production, distribution and use of the energy to be as technological efficient as possible, and incentives to save energy at the end-user should also be strengthened. In order to realize the transition smoothly and effectively, power conversion systems will continue to play an essential role. Using highly efficient power electronics in generation, transmission/distribution and end-user application, together with advanced controls, can pave the way for renewable energy resources. In view of this, some of the most promising renewable candidates like wind power and photovoltaic, which are becoming a significant part in the electricity production, are explored in this paper. Issues like technology demands, power converter topologies, and control structures are addressed. Some special focuses are also paid on the emerging trends in power electronics development for those systems.

This paper describes a methodology to design a hybrid renewable energy system over a certain planning horizon. Traditionally a system plan was developed to achieve a minimum cost objective (MCO) while satisfying the energy demand, reliability, stability and battery constraints. The minimum emissions objective (MEO) is now an important target to achieve subject to the above mentioned constraints. Each of the above problems may be solved using linear programming, but minimizing the two preceding objectives at the same time forms a multi-objective problem which is solved by the epsiv-constraint and the goal attainment methods. The epsiv-constraint method minimizes the total cost while the emissions are less than a certain value epsiv determined by the linear programming when minimizing emissions only or by the designer. The goal attainment method tries to balance all the objectives and make them as close as possible to the initial goals determined by MCO and MEO. A case study is presented to illustrate the applicability and the usefulness of the proposed method.

PEM electrolysis is a viable alternative for generation of hydrogen from renewable energy sources. Several possible applications are discussed, including grid independent and grid assisted hydrogen generation, use of an electrolyzer for peak shaving, and integrated systems both grid connected and grid independent where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed. Specific issues regarding the use of PEM electrolyzer in the renewable energy systems are addressed, such as sizing of electrolyzer, intermittent operation, output pressure, oxygen generation, water consumption and efficiency.

This article examines the strategy of electrification for Sarawak which centers on large-scale hydroelectric projects. Drawing from extensive in-field interviews of stakeholders in Sarawak who are affected by the soon-to-be-completed 2400megawatt (MW) Bakun Hydroelectric Project, this article presents documentary evidence that these “hard path” mega energy projects are economically, socially and ecologically sub-optimal. The study suggests that more rigorous development

The electrical energy consumption continues to grow and more applications are based on electricity. We can expect that more 60 % of all energy consumption will be converted and used as electricity. Therefore, it is a demand that production, distribution and use of electrical energy are done as efficient as possible. Further, the emerging climate changes is arguing to find sustainable future solutions. Of many options, two major technologies will play important roles to solve parts of those future problems. One is to change the electrical power production from conventional, fossil based energy sources to renewable energy sources. Another is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss trends of the most emerging renewable energy sources, wind energy and photovoltaics, which by means of power electronics are changing and challenging the future electrical infrastructure but also contributes steadily more to non-carbon based electricity production.

This paper describes a methodology to design a hybrid renewable energy system over a certain planning horizon. Traditionally a system plan was developed to achieve a minimum cost objective (MCO) while satisfying the energy demand, reliability, stability and battery constraints. The minimum emissions objective (MEO) is now an important target to achieve subject to the above mentioned constraints. Each of the above problems may be solved using linear programming, but minimizing the two preceding objectives at the same time forms a multi-objective problem which is solved by the epsiv-constraint and the goal attainment methods. The epsiv-constraint method minimizes the total cost while the emissions are less than a certain value epsiv determined by the linear programming when minimizing emissions only or by the designer. The goal attainment method tries to balance all the objectives and make them as close as possible to the initial goals determined by MCO and MEO. A case study is presented to illustrate the applicability and the usefulness of the proposed method.

Much more efforts have been made on the integration of renewable energies into the grid in order to meet the imperative demand of a clean and reliable electricity generation. In this case, the grid stability and robustness may be violated due to the intermittency and interaction of the solar and wind renewables. Thus, in this chapter, advanced control strategies, which can enable the power conversion efficiently and reliably, for both photovoltaic (PV) and wind turbines power systems are addressed in order to enhance the integration of those technologies. Related grid demands have been presented firstly, where much more attention has been paid on specific requirements, like Low Voltage Ride-Through (LVRT) and reactive power injection capability. To perform the functions of those systems, advanced control strategies are presented with much more emphasis on the LVRT operation with reactive power injection for both single-phase and three-phase systems. Other control strategies like constant power generation control for PV systems to further increase the penetration level, and the improvements of LVRT performance for a doubly fed induction generator based wind turbine system by means of hardware protection solutions are also discussed in this chapter.

Energy resources and their utilization intimately relate to sustainable development. In attaining sustainable development, increasing the energy efficiencies of processes utilizing sustainable energy resources plays an important role. The utilization of renewable energy offers a wide range of exceptional benefits. There is also a link between exergy and sustainable development. A sustainable energy system may be regarded as a cost-efficient, reliable, and environmentally friendly energy system that effectively utilizes local resources and networks. Exergy analysis has been widely used in the design, simulation and performance evaluation of energy systems.The present study comprehensively reviews exergetic analysis and performance evaluation of a wide range of renewable energy resources (RERs) for the first time to the best of the author's knowledge. In this regard, general relations (i.e., energy, exergy, entropy and exergy balance equations along with exergy efficiency, exergetic improvement potential rate and some thermodynamic parameters, such as fuel depletion ratio, relative irreversibility, productivity lack and exergetic factor) used in the analysis are presented first. Next, exergetically analyzed and evaluated RERs include (a) solar energy systems; (a1) solar collector applications such as solar water heating systems, solar space heating and cooling, solar refrigeration, solar cookers, industrial process heat, solar desalination systems and solar thermal power plants), (a2) photovoltaics (PVs) and (a3) hybrid (PV/thermal) solar collectors, (b) wind energy systems, (c) geothermal energy systems, (c1) direct utilization (district heating, geothermal or ground-source heat pumps, greenhouses and drying) and (c2) indirect utilization (geothermal power plants), (d) biomass, (e) other renewable energy systems, and (f) country based RERs. Studies conducted on these RERs are then compared with the previously ones in tabulated forms, while the Grassmann (or exergy flow) diagrams, which are a very useful representation of exergy flows and losses, for some RERs are given. Finally, the conclusions are presented. It is expected that this comprehensive study will be very beneficial to everyone involved or interested in the exergetic design, simulation, analysis and performance assessment of RERs.

This paper discusses the perspective of renewable energy (wind, solar, wave and biomass) in the making of strategies for a sustainable development. Such strategies typically involve three major technological changes: energy savings on the demand side, efficiency improvements in the energy production, and replacement of fossil fuels by various sources of renewable energy. Consequently, large-scale renewable energy implementation plans must include strategies for integrating renewable sources in coherent energy systems influenced by energy savings and efficiency measures. Based on the case of Denmark, this paper discusses the problems and perspectives of converting present energy systems into a 100% renewable energy system. The conclusion is that such development is possible. The necessary renewable energy sources are present, and if further technological improvements of the energy system are achieved the renewable energy system can be created. Especially technologies of converting the transportation sector and the introduction of flexible energy system technologies are crucial. r

Photovoltaic energy has nowadays an increased importance in electrical power applications, since it is considered as an essentially inexhaustible and broadly available energy resource. However, the output power provided via the photovoltaic conversion process depends on solar irradiation and temperature. Therefore, to maximize the efficiency of the photovoltaic energy system, it is necessary to track the maximum power point of the PV array. The present paper proposes a maximum power point tracker (MPPT) method, based on fuzzy logic controller (FLC), applied to a stand-alone photovoltaic system. It uses a sampling measure of the PV array power and voltage then determines an optimal increment required to have the optimal operating voltage which permits maximum power tracking. This method carries high accuracy around the optimum point when compared to the conventional one. The stand-alone photovoltaic system used in this paper includes two bi-directional DC/DC converters and a lead-acid battery bank to overcome the scare periods. One converter works as an MPP tracker, while the other regulates the batteries state of charge and compensates the power deficit to provide a continuous delivery of energy to the load. The Obtained simulation results show the effectiveness of the proposed fuzzy logic controller.

Renewable energy is becoming economic in all markets as its rapid growth results in more competitive prices. It is particularly appropriate and increasingly being adopted for providing electric power services to rural areas in developing countries unlikely to be served by grid electricity. Policies needed to implement renewable energy systems in rural areas are discussed in this paper. Most prominent are removal of subsidies to traditional energy primarily benefiting the wealthiest; involving the local populace in decision making; educating financial institutions about the economics of investing in renewable energy systems and creating investment vehicles appropriate to financing them in poor localities; training personnel on management, maintenance and drafting contracts; requiring vendor provision of maintenance and parts; and effective regulation and oversight of system management and financing.

The use of renewable energy sources are increased because of the depletion of natural resources and the increasing pollution level from energy production. The wind energy and the solar energy are most widely used among the renewable energy sources. Power electronics is needed in almost all kinds of renewable energy system. It controls the renewable source and interfaces with the load effectively, which can be grid-connection or working in stand-alone mode. In this paper, overview of wind and photovoltaic energy systems are introduced. Next, the power electronic circuits behind the most common wind and photovoltaic configurations are discussed. Finally, their controls and important requirements for grid connection are explained.

Traditionally, when designing an LCL-filter, a three-phase inverter is simplified as a single-phase inverter for analysis and the output phase voltage is used to calculate the inverter-side current harmonics and to design inverter-side inductor. However, for a three-phase three-wire grid-tied system, the output current harmonics of inverter are directly affected by the output line to line voltage. Hence, this paper proposes a new method to analyze the inverter output current harmonics by using the equivalent phase voltage of the three phase inverter. Based on this, a step by step design method of the high order power filter is introduced. Simulations are carried out to verify the accuracy and the validity of the proposed methods through a 6 kW, 380V/50 Hz grid-connected inverter model with three different types of high order power filters.

A sustainable energy system may be defined as a cost-effective, reliable, and environment friendly energy system that effectively utilizes local resources and networks. For providing a sustainable energy supply, renewable energy sources appear to be the one of the most efficient and effective solutions. This paper presents sizing of hybrid energy system consisting of solar, wind, micro hydro, biomass, diesel and battery using HOMER of an un electrified area and also presents environmental aspects of different configuration.

Nowadays, uninterruptible power supply (UPS) systems are in use throughout the world, helping to supply a wide variety of critical loads, in situations of power outage or anomalies of the mains. This article describes the most common line problems and the relationship between these and the different existing kinds of UPS, showing their operation modes as well as the existent energy storage systems. It also addresses an overview of the control schemes applied to different distributed UPS configurations. Finally, it points out the applicability of such systems in distributed generation, microgrids, and renewable energy systems.

Operating conditions in off-grid renewable energy systems (RES) vary significantly in different applications and locations. To describe RES and the operating conditions of their components it is useful to define categories of similar operating conditions. Categories can also be used for lifetime considerations of RES components, for making recommendations and for analysing the properties and performance of a RES and its components. Categories support system designers and an economic analysis. This paper describes the process and the results of creating RES categories of similar operating conditions for batteries. Categories are defined in such a way that batteries belonging to the same category are subjected to similar operating conditions and a similar combination of stress factors. The results provide a comprehensive overview of battery operating conditions in existing off-grid renewable energy systems. This work is part of the EU research project Benchmarking. 1

6-37-1 topology, r, RMSE, and MAE values were found to be 0.968, 3.09, and 2.57, respectively. Obtained results showed that ANN model outperformed HS model and can be successfully used for estimating the daily GSR for Tehran province and any other location. 177 178 RAMEDANI, OMID, AND KEYHANI DNI data is required. Solar thermal power plants are essentially Concentrating Solar Power (CSP) units. For designing solar thermal power plants, DNI data is therefore a prerequisite.

At WGC 1995 in Florence a paper was presented that brought to the attention of the worldwide geothermal community the increasing activity in geothermal heat pumps. With increasing pressures for reductions in building energy consumption and rising targets for reductions in CO2 emissions from buildings, the drivers for installing geothermal heat pumps are all going in the right direction. An increasing number of countries - some of them not traditionally associated with conventional geothermal activity, now have vigorous geothermal heat pump programmes. Other countries are exploring the potential of these systems. From small domestic installations in social housing to multi megawatt systems and all sizes in between – geothermal heat pumps are on the increase. Ten years on this paper assesses current progress in the development and installation of these high efficiency, long lived, low carbon, renewable energy systems.

The use of distributed energy resources (DER) is increasingly being pursued as a supplement and an alternative to large conventional central power stations. The specification of a power electronics interface is subject to requirements related not only to the renewable energy source itself but also to its effects on power system operation, especially where the intermittent energy source constitutes a significant part of the total system capacity. In this paper, new trends in power electronics for the integration of wind and photovoltaic power generators are presented. A review of appropriate storage systems technology used for the integration of intermittent renewable energy sources is also introduced. Discussions about common and future trends in renewable energy systems based on reliability and maturity of each technology are presented.

The global electrical energy consumption is still rising and there is a steady demand to increase the power capacity. It is expected that it has to be doubled within 20 years. The production, distribution and use of the energy should be as technological efficient as possible and incentives to save energy at the end-user should also be set up. Deregulation of energy has lowered the investment in larger power plants, which means the need for new electrical power sources may be very high in the near future. Two major technologies will play important roles to solve the future problems. One is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. An other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss some of the most emerging renewable energy sources, wind energy and photovoltaic, which by means of power electronics are changing from being minor energy sources to be acting as important power sources in the energy system

High cost of renewable energy systems has led to its slow adoption in many countries. Hence, it is vital to select an appropriate size of the system in order to reduce the cost and excess energy produced as well as to maximize the available resources. The sizing of hybrid system must satisfy the LPSP (Loss of Power Supply Probability) which determines the ability of the system to meet the load requirements. Once the lowest configurations are determined, the cost of the system must then be taken into consideration to determine the system with the lowest cost. The optimization methodology proposed in this paper uses the ANFIS (Adaptive Neuro-Fuzzy Inference System) to model the PV and wind sources. The algorithm developed is compared to HOMER (Hybrid Optimization Model for Electric Renewables) and HOGA (Hybrid Optimization by Genetic Algorithms) software and the results demonstrate an accuracy of 96% for PV and wind. The optimized system is simulated in PSCAD/EMTDC and the results show that low excess energy is achieved. The optimized system is also able to supply power to the load without any renewable sources for a longer period, while conforming to the desired LPSP.