Techno-economical optimization of hybrid pv/wind/battery system using Neuro-Fuzzy

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.     

Optimization of autonomous hybrid systems with hydrogen storage: Life cycle assessment

The design of autonomous systems for the rural electrification is a complex task due to the diversity of variables involved in such processes. The absence of programs and methods that carry out this task in a clear and precise manner constitutes a barrier to the dissemination of these systems, although some tools have been developed that present other possible limitations. The exclusion of the environmental dimension in the design and evaluation process of hybrid systems means that the true benefits are not evaluated in terms of quality and quantity. In an attempt to overcome such deficiencies, this work presents a new method of design; approached from the multi‐objective optimization of systems. The multi‐objective optimization by means of enumerative search implemented by the Hybrid Optimization Model for Electric Renewable program is used to generate a set of solutions optimized economically by the value of the net present cost (NPC). The analysis of greenhouse gas emissions (in tCO₂‐eq.) in the life cycle of each one of the system components is carried out and a set of solutions with the values of the two objective functions is generated, namely NPC and NAE_SLC (net avoided emissions in the system life cycle). The method is applied to a case study in a Cuban rural community. The compromise solution obtained by means of the proposed algorithm includes a wind turbine (WT) of 25.4 and 8 kW of photovoltaic panels, while that of the HOGA includes a WT of 76 and 21 kW of photovoltaic panels. Both commitment solutions consider hydrogen storage instead of storage in batteries, as a better option for the energy storage. Copyright © 2011 John Wiley & Sons, Ltd.     

DESIGN OF HYBRID-PHOTOVOLTAIC POWER GENERATOR, WITH OPTIMIZATION OF ENERGY MANAGEMENT

A methodology is developed for calculating the correct size of a photovoltaic (PV)-hybrid system and for optimizing its management. The power for the hybrid system comes from PV panels and an engine-generator – that is, a gasoline or diesel engine driving an electrical generator. The combined system is a stand-alone or autonomous system, in the sense that no third energy source is brought in to meet the load. Two parameters were used to characterize the role of the engine-generator: denoted SDM and SAR, they are, respectively, the battery charge threshold at which it is started up, and the storage capacity threshold at which it is stopped, both expressed as a percentage of the nominal battery storage capacity. The methodology developed is applied to designing a PV-hybrid system operating in Corsica, as a case study. Various sizing configurations were simulated, and the optimal configuration that meets the autonomy constraint (no loss of load) was determined, by minimizing of the energy cost. The influence of the battery storage capacity on the solar contribution is also studied. The smallest energy cost per kWh was obtained for a system characterized by an SDM=30% and an SAR=70%. A study on the effects of component lifetimes on the economics of PV-hybrid and PV stand-alone systems has shown that battery size can be reduced by a factor of two in PV-hybrid systems, as compared to PV stand-alone systems.     

Optimisation and techno-economic analysis of autonomous photovoltaic–wind hybrid energy systems in comparison to single photovoltaic and wind systems

A techno-economic analysis for autonomous small scale photovoltaic–wind hybrid energy systems is undertaken for optimisation purposes in the present paper. The answer to the question whether a hybrid photovoltaic–wind or a single photovoltaic or wind system is techno-economically better is also sought. Monthly analysis of 8 year long measured hourly weather data shows that solar and wind resources vary greatly from one month to the next. The monthly combinations of these resources lead to basically three types of months: solar-biased month, wind-biased month and even month. This, in turn, leads to energy systems in which the energy contributions from photovoltaic and wind generators vary greatly. The monthly and yearly system performances simulations for different types of months show that the system performances vary greatly for varying battery storage capacities and different fractions of photovoltaic and wind energy. As well as the system performance, the optimisation process of such hybrid systems should further consist of the system cost. Therefore, the system performance results are combined with system cost data. The total system cost and the unit cost of the produced electricity (for a 20 year system lifetime) are analysed with strict reference to the yearly system performance. It is shown that an optimum combination of the hybrid photovoltaic–wind energy system provides higher system performance than either of the single systems for the same system cost for every battery storage capacity analysed in the present study. It is also shown that the magnitude of the battery storage capacity has important bearings on the system performance of single photovoltaic and wind systems. The single photovoltaic system performs better than a single wind system for 2 day storage capacity, while the single wind system performs better for 1.25 day storage capacity for the same system cost.     

Modeling,control and simulation of a photovoltaic /hydrogen/ supercapacitor hybrid power generation system for grid-connected applications

Hybrid renewable energy systems (HRES) should be designed appropriately with an adequate combination of different renewable sources and various energy storage methods to overcome the problem of intermittency of renewable energy resources. Focusing on the inevitable impact on the grid caused by strong randomicity and apparent intermittency of photovoltaic (PV) generation system, modeling and control strategy of pure green and grid-friendly hybrid power generation system based on hydrogen energy storage and supercapacitor (SC) is proposed in this paper. Aiming at smoothing grid-connected power fluctuations of PV and meeting load demand, the alkaline electrolyzer (AE) and proton exchange membrane fuel cell (PEMFC) and SC are connected to DC bus of photovoltaic grid-connected generation system. Through coordinated control and power management of PV, AE, PEMFC and SC, hybrid power generation system friendliness and active grid-connection are realized. The validity and correctness of modeling and control strategies referred in this paper are verified through simulation results based on PSCAD/EMTDC software platform.     

Genetic fuzzy rule extraction for optimised sizing and control of hybrid renewable energy hydrogen systems

A major challenge related to the design of a hybrid renewable energy hydrogen system is which energy sources to include and at what capacity, for regionally different potentials of renewable energy and hydrogen demand. In addition, once the plant is in operation, control variables need to be optimised. The problem resorts to an area of multiple criteria decision making referred to as multi-objective optimisation. The results obtained from these type of algorithms include not only one optimal solution, but a set of optimal solutions (Pareto front) thereby offering a system designer several options. This set of solutions can be hard to interpret and a method is needed to automatically extract useful design and control strategies from this information. A methodology that is quite successful in deriving human interpretable rules from this type of information is genetic fuzzy systems. In this work a k-means clustering algorithm is used to generate membership functions and a fuzzy rule-base is trained by means of a genetic algorithm. The genetic fuzzy system obtained is reduced by determining the minimum number of rules followed by a membership function reduction process. The reduced genetic fuzzy system is deemed more interpretable. Geographic weather data from three different sites are used to generate data to be used in the genetic fuzzy method. Results show that the technique provides valuable information that can be used for the design of such hybrid renewable energy hydrogen production systems.     

Optimal sizing of stand-alone hybrid systems based on PV/WT/FC by using several methodologies

This paper presents a comparative study of four sizing methods for a stand-alone hybrid generation system integrating renewable energies (photovoltaic panels and wind turbine) and backup and storage system based on battery and hydrogen (fuel cell, electrolyzer and hydrogen storage tank). Two of them perform a technical sizing. In one case, the sizing is based on basic equations, and in the other case, an optimal technical sizing is achieved by using Simulink Design Optimization. The other two methods perform an optimal techno-economical sizing by using the hybrid system optimization software HOMER and HOGA, respectively. These methods have been applied to design a stand-alone hybrid system which supplies the load energy demand during a year. A MATLAB-Simulink model of the hybrid system has been used to simulate the performance of hybrid system designed by each method for the stand-alone application under study in this work. The results are reported and discussed in the paper.     

Model-based optimal control of a hybrid power generation system consisting of photovoltaic arrays and fuel cells

Hybrid renewable energy systems are expected to become competitive to conventional power generation systems in the near future and, thus, optimization of their operation is of particular interest. In this work, a hybrid power generation system is studied consisting of the following main components: photovoltaic array (PV), electrolyser, metal hydride tanks, and proton exchange membrane fuel cells (PEMFC). The key advantage of the hybrid system compared to stand-alone photovoltaic systems is that it can store efficiently solar energy by transforming it to hydrogen, which is the fuel supplied to the fuel cell. However, decision making regarding the operation of this system is a rather complicated task. A complete framework is proposed for managing such systems that is based on a rolling time horizon philosophy.     

Development of the hard and soft constraints based optimisation model for unit sizing of the hybrid renewable energy system designed for microgrid applications

The hybrid energy systems (HESs) based electricity generation system has become a more attractive solution for rural electrification nowadays. Economically feasible and technically reliable HESs are solidly based on an optimisation stage. This article discusses about the optimal unit sizing model with the objective function to minimise the total cost of the HES. Three typical rural sites from southern part of India have been selected for the application of the developed optimisation methodology. Feasibility studies and sensitivity analysis on the optimal HES are discussed elaborately in this article. A comparison has been carried out with the Hybrid Optimization Model for Electric Renewable optimisation model for three sites. The optimal HES is found with less total net present rate and rate of energy compared with the existing method     

Sizing optimization of a stand-alone street lighting system powered by a hybrid system using fuel cell,PV and battery

Currently commercialised stand-alone street lighting systems based on the classical configuration coupling photovoltaic cells (PV) and battery cannot work all the year round in regions that are far from the equator. To improve the classical system, a hybrid system coupling a PV, a battery and a fuel cell is proposed. However, the sizing method of hybrid systems is a key issue in obtaining the cheapest system. To optimise the system, an original time-saving method is applied. Two optimization methods are used: first the genetic algorithms, then the simplex algorithms. A simulation model is used to evaluate the validity of the different hybrid configurations. After presenting the problem of stand-alone street lighting, the optimization methodology and the simulation model are detailed. Finally, an optimal configuration is obtained and shows that a 60 W street light would cost 7150€ with a lifetime of 25 years. The optimised parameters are also given and analysed.     

Using whole annealing genetic algorithms for the turbine cascade inverse design problem

INTRODUCTIONInthelastfewyearstherehajsbeenagrowinginterestinthenumericalsolutionofconstrainedoptimizationproblemsofturbinegovernedbytheEulerorNavier-Stokesequations.Developmelltofturbinecascadeswithoptimumaerodynamicefficiencyhaslongbeenadesignchalle...     

Optimisation and techno-economic feasibility analysis of hybrid (photovoltaic/wind/fuel cell) energy systems in Kerman,Iran; considering the effects of electrical load and energy storage technology

A hybrid (photovoltaic, PV/wind/fuel cell, FC) system comprising different combinations of PV arrays, wind turbine, hydrogen tank, electrolyser, and FC has been investigated for stand-alone applications. Load demand was the electrical requirements of atypical residential apartment having a total area of 500 m² with a peak electrical load of 35 kW and a yearly load of 24.4 MWh in Kerman, Iran. The assessment criterion for the analysis was levellised cost of energy of each system configuration. National Renewable Energy Laboratory's Hybrid Optimization Model for Electric Renewable software was utilised as the assessment tool of the present study. The effect of electrical load profile on the optimisation results has also been investigated considering a demand load profile with a low peak of 12 kW. Also, a comparison was made between the hybrid (PV/wind/diesel/bat) systems and the hybrid (PV/wind/FC) system of the current study at different fuel price scenarios.     

Study on optimal configuration of the grid-connected wind–solar–battery hybrid power system

The capacity allocation of each energy unit in the grid-connected wind–solar–battery hybrid power system is a significant segment in system design. In this paper, taking power grid dispatching into account, the research priorities are as follows: (1) We establish the mathematic models of each energy unit in the hybrid power system. (2) Based on dispatching of the power grid, energy surplus rate, system energy volatility and total cost, we establish the evaluation system for the wind–solar–battery power system and use a number of different devices as the constraint condition. (3) Based on an improved Genetic algorithm, we put forward a multi-objective optimisation algorithm to solve the optimal configuration problem in the hybrid power system, so we can achieve the high efficiency and economy of the grid-connected hybrid power system. The simulation result shows that the grid-connected wind–solar–battery hybrid power system has a higher comprehensive performance; the method of optimal configuration in this paper is useful and reasonable.     

Optimal economic study of hybrid PV-wind-fuel cell system integrated to unreliable electric utility using hybrid search optimization technique

This study addresses the problem of power outages in distant districts by taking advantage of the available renewable energy resources in the surrounding environment. This was done by proposing connecting the utility to a hybrid system constituting from photovoltaic (PV), wind turbine (WT), and fuel cell (FC) systems where this hybrid system is considered as a backup system that works when the grid is unavailable. This hybrid system proposed is used for feeding the load to a tourist resort in Hurghada, Egypt.The design of the introduced system has taken into consideration the cost of purchasing electric energy and the profit from selling it to the utility network. Component scaling was implemented to improve the net present cost of the proposed system using two grouped meta-heuristic techniques, which are the Hybrid Firefly and Harmony Search optimization technique (HFA/HS) and compared to the particle swarm optimization (PSO) technique.Simulation results have shown that the optimal system for solving the grid unavailability consists of eighty PVs, two WTs, twenty FCs, forty-one electrolyzers, and one hundred eighteen hydrogen tanks. The results also showed that the volume of exchange with the grid has reached 4 GW of purchase and 3 GW of sale. It is manifest from the results that the suggested system is economically viable with an LCOE of 0.0628 $/kWh, which is less than the purchase of electricity from the grid for commercial users in Egypt, which is 0.1 $/kWh.     

Multicriteria Design of Hybrid Power Generation Systems Based on a Modified Particle Swarm Optimization Algorithm

Multisource hybrid power generation systems are a type of representative application of the renewables' technology. In this investigation, wind turbine generators, photovoltaic panels, and storage batteries are used to build hybrid generation systems that are optimal in terms of multiple criteria including cost, reliability, and emissions. Multicriteria design facilitates the decision maker to make more rational evaluations. In this study, an improved particle swarm optimization algorithm is developed to derive these nondominated solutions. Hybrid generation systems under different design scenarios are designed based on the proposed approach. First, a grid-linked hybrid system is designed without incoroprating system uncertainties. Then, adequacy evaluation is conducted based on probabilistic methods by accounting for equipment failures, time-dependent sources of energy, and stochastic generation/load variations. In particular, due to the unpredictability of wind speed and solar insolation as well as the random load variation, time-series models are adopted to reflect their stochastic characteristics. An adequacy evaluation procedure including time-dependent sources, is adopted. Sensitivity studies are also carried out to examine the impacts of different system parameters on the overall design performance.      

Optimal hybrid renewable energy systems for energy security: a comparative study

A hybrid power system may be used to reduce dependency on either conventional energy or renewable systems. This article deals with the sizing, generator running hours, sensitivity analysis, optimisation, and greenhouse gas emission analysis of hybrid renewable energy systems (HRES). Two locations have been selected where the feasibility of using different hybrid systems is studied for the same load demand. One site is the small remote community of Amini in the Lakshadweep Islands, located in southern India in the Arabian Sea, where solar and/or wind energy is always available throughout the year to provide energy security. Another place is the rural township of Hathras, in the northern Indian state of Uttar Pradesh, where agricultural biomass is found in abundance for the whole year. A comparative study has been made for the two locations for the same load demand by simulating HRES. To achieve the goal of simulation, the hybrid optimisation model for electric renewables (HOMER) software of the National Renewable Energy Laboratory, USA, is used. An optimisation model of a hybrid renewable system has been prepared which simplifies the task of evaluating the design of an off-grid/standalone system. After simulating all possible system equipment with their sizes, a list of many possible configurations may be evaluated and sorted by net present cost to compare the design options. An elaborate sensitivity analysis has been used for each input variable; the whole optimisation process is repeated to get simulated system configurations     

A stand-alone hybrid photovoltaic,fuel cell and battery system: A case study of Tocantins,Brazil

Abstract: This paper aimed to evaluate the use of a photovoltaic-fuel cell-battery system to supply electric power in an isolated community in the Amazon region. The study focused on technical and cost issues of a pilot-project set up in an environmental protection area, located in the state of Tocantins, Brazil. A comparative analysis of the costs of the hybrid system after optimization was made with the aid of the HOMER^© (Hybrid Optimization Model for Electric Renewables) program. The analysis shows that the optimal system's initial cost, net present cost, and electricity cost with the hydrogen storage system is US$ 87,138; US$102,323; and US$ 1.351/kWh, respectively. Components are costly (fuel cell and electrolyzer), with the photovoltaic modules and the electrolyzer presenting the main cost of system. Based on the results, the study confirmed that the best option for storing energy from photovoltaic systems is still the use of batteries. In the short term, implementation of hybrid photovoltaic-fuel cell-battery system in the region remains prohibitive due to the high cost of its components.     

Dynamic modeling and sizing optimization of stand-alone photovoltaic power systems using hybrid energy storage technology

Economic and environmental concerns over fossil fuels encourage the development of photovoltaic (PV) energy systems. Due to the intermittent nature of solar energy, energy storage is needed in a stand-alone PV system for the purpose of ensuring continuous power flow. Three stand-alone photovoltaic power systems using different energy storage technologies are studied in this paper. Key components including PV modules, fuel cells, electrolyzers, compressors, hydrogen tanks and batteries are modeled in a clear way so as to facilitate the evaluation of the power systems. Based on energy storage technology, a method of ascertaining minimal system configuration is designed to perform the sizing optimization and reveal the correlations between the system cost and the system efficiency. The three hybrid power systems, i.e., photovoltaic/battery (PV/Battery) system, photovoltaic/fuel cell (PV/FC) system, and photovoltaic/fuel cell/battery (PV/FC/Battery) system, are optimized, analyzed and compared. The obtained results indicate that maximizing the system efficiency while minimizing system cost is a multi-objective optimization problem. As a trade-off solution to the problem, the proposed PV/FC/Battery hybrid system is found to be the configuration with lower cost, higher efficiency and less PV modules as compared with either single storage system.     

光水混合发电系统优化策略研究

为了提高独立能源发电的可靠性与运行效率,结合光水发电系统的混合发电模式,搭建出光水混合发电系统的优化模型,并基于改进型粒子群优化算法(CPSO)对混合光水发电系统进行仿真计算,比较了混合发电与单一发电系统中传输功率及效益。结果表明,通过对光水混合发电系统中水电优化,解决了光伏发电不稳定问题,更好地利用了太阳能与水电资源优化互补的特性,实现了效益最大化。     

Hybrid photovoltaic/thermal solar systems

We present test results on hybrid solar systems, consisting of photovoltaic modules and thermal collectors (hybrid PV/T systems). The solar radiation increases the temperature of PV modules, resulting in a drop of their electrical efficiency. By proper circulation of a fluid with low inlet temperature, heat is extracted from the PV modules keeping the electrical efficiency at satisfactory values. The extracted thermal energy can be used in several ways, increasing the total energy output of the system. Hybrid PV/T systems can be applied mainly in buildings for the production of electricity and heat and are suitable for PV applications under high values of solar radiation and ambient temperature. Hybrid PV/T experimental models based on commercial PV modules of typical size are described and outdoor test results of the systems are presented and discussed. The results showed that PV cooling can increase the electrical efficiency of PV modules, increasing the total efficiency of the systems. Improvement of the system performance can be achieved by the use of an additional glazing to increase thermal output, a booster diffuse reflector to increase electrical and thermal output, or both, giving flexibility in system design.