Stand-alone Hybrid Energy System Research Articles

Optimal Design of a Standalone Hybrid Energy System for a Covid-19 Quarantine Center Energization

This work is motivated by the current situation in the world in particular the spread of COVID-19. Building quarantine centers is one of the most important means used in combating the Corona epidemic, but connecting these centers to the electricity distribution network at the appropriate time is not always possible. This paper proposed a Hybrid off-grid Energy System (HES) to effectively energies the quarantine centers economically and environmentally. To achieve this aim, the load profile of the quarantine center is estimated, the system components are modeled and the system design is optimized. In addition, the developed approach was tested using a real case study considering realistic input data. HOMER-pro program is used to simulate and optimize the system design. The results revealed the potential of the HES to provide environment-friendly, cost-effective, and affordable electricity for the studied quarantine center, as compared to only diesel generators system. For the considered case study, it is found that the PV-Wind-Diesel hybrid power system is able to cover the connected load with the lowest cost in comparison to other possible HES structures. It also environmentally friendly as it has the least harmful emissions. Finally, it is proved that the developed approach gives a reasonable solution to the decision-makers to find a fast, economic and reliable solution to energies the quarantine centers.

Enhanced design of an offgrid PV-battery-methanation hybrid energy system for power/gas supply

Extensive studies have been carried out on various hybrid energy systems (HESs) for providing electricity to off-grid areas. However, a standalone HES that is capable of providing power and gas, has been less studied. In this paper, a standalone Photovoltaic (PV)-battery-methanation HES is proposed to provide adequate, reliable and cost-effective electricity and gas to the local consumers. Identifying a potential solution to maximize the reliability of the system, asked by consumers, and to minimize costs required by the investors is challenging. Bi-level programming is adopted in this study to tackle the pre-mentioned issue. In the outer layer, an optimal design is obtained by means of particle swarm optimization. In the inner layer, an optimal operation strategy is found under the optimal design of the outer layer using sequential quadratic programming. The results indicate that 1) The bi-level programming used in this study can find the optimal solution; 2) The proposed HES is proved to be able to supply power and gas simultaneously. 3) Compared with the right most and leftmost points on Pareto set, the total costs are reduced by 17.77% and 2.16%.

Multi-objective optimization and cost-based output pricing of a standalone hybrid energy system integrated with desalination

The design and operation of hybrid energy systems, which are relevant to remote islands characterized by energy and water supply shortage, have been extensively investigated. However, determining the costs of different system outputs is still a challenging task. In this study, a multi-objective optimization was performed to obtain the optimal design parameters of a hybrid energy system integrated with desalination. As each consumer demand (inclusive of electrical, cooling, and water demands) is highly coupled to the other, output pricing was performed based on cost allocation using the cooperative game theory. The results show that cooling, electricity, and desalinized water can be co-generated efficiently and economically, and the electrical, cooling, and water demands should bear 13.40%, 53.90%, and 32.70%, respectively, of the annualized costs of the entire hybrid energy system. In the proposed model, the cooling demand has the strongest coupling characteristic, whereas the electrical demand has the weakest, because the electricity waste from the photovoltaic/thermal panels allows easier integration of the cooling demands with other demands, for the consumption of excess solar power.

Energy allocation strategy based on fuzzy control considering optimal decision boundaries of standalone hybrid energy systems

Energy management and cost control are inevitable problems that restrict the development of standalone distributed renewable energy systems used in buildings. This paper presents a flexible allocation strategy based on a two-stage fuzzy logic controller to address these problems. Special attention has been paid to the management of stored energy and emergency resource. Decision boundaries are optimised based on actual operating characteristics of units. The fuzzy controller considering decision boundaries is more objective and realizes more accurate real-time energy management with less cost. Sensitivity analysis is conducted for uncertainty factors, which would affect decision boundaries. The effectiveness and advantages of the proposed strategy are verified through a typical hybrid system on an isolated island in the South China Sea. Results indicate that fuzzy controller considering decision boundaries saves 14.15% of the operating cost compared to fuzzy controller without considering decision boundaries, and it saves 20.45% when compared to the fixed priority strategy without flexible allocation. Moreover, its loss of power supply probability is the smallest, which is only 0.72%. A maximum synergy between the power supply and cooling demand is achieved. This novel controller performs better in reliability, economy, and response speed for a real time system. The proposed strategy has a positive effect on practical application of hybrid renewable energy systems for buildings in isolated areas.

Optimization of PV Based Standalone Hybrid Energy System using Cuckoo Search Algorithm

Background: Renewable sources of energy have emerged as a promising eco-friendly alternative to the conventional and non-renewable sources of energy. However, highly variable and intermittent nature of renewable sources acts as a big hurdle in their widespread adoption. Hybrid energy systems provide an efficient and reliable solution to this issue, especially for the non-grid connected or stand-alone systems. Objective: The study deals with the design and optimization of a stand-alone hybrid renewable energy system. Methods: Two different configurations consisting of PV/W/B/DG have been modeled and optimized for lower annualized cost using cuckoo search, a meta-heuristic algorithm. Analysis of these system configurations has been carried to meet the energy demand at the least annualized cost. Results and Conclusion: Using a real world data for an existing educational organization in India, it is proven that the proposed optimization method meets all the requirements of the system and PV/B/DG configuration returns a lower annualized cost as well as leads to lower emissions.

Optimal designing and management of a stand-alone hybrid energy system using meta-heuristic improved sine–cosine algorithm for Recreational Center, case study for Iran country

In this paper, optimal designing and energy management of hybrid photovoltaic/wind/fuel cell (PV/WT/FC) system is presented with cost of hybrid system life span (CHSLS) minimizing and considering loss of load interruption probability (LOLIP) for Recreational Center of Gonbad (RCOG), a remote area region in Iran country using actual irradiance and wind speed data of this region. A meta-heuristic improved sine–cosine algorithm (ISCA) is used based on nonlinearly decreasing inertia weight strategy (NDIWS) for improving global and local search of the conventional SCA to find the optimal combination of hybrid system. In designing problem the optimal size of hybrid system components is determined using ISCA considering CHLS and LOLIP to satisfy the RCOG load demand in most cost-effective way. The performance of the proposed ISCA is compared with conventional SCA and well-known PSO methods in different combinations and under LOLIP changing conditions. Simulation results showed that the ISCA finds easily the optimal combination as PV/WT/FC system with lower CHSLS and better LOLIP. Also WT/FC system is not economical due to high CHSLS for RCOG. The results demonstrated that the average cost of per kW RCOG load supply using the PV/WT/FC for maximum LOLIP of 1% is equal to 0.87$ and for maximum LOLIP of 5% is 0.76$. The results showed the contribution and management of PV, WT and fuel cell together as PV/WT/FC is made a reliable and cost-effective energy system to supply the remote area application like RCOG. Moreover superiority of the ISCA than the SCA and PSO is proved with better convergence speed and accuracy. Also, the effect of some effective factors on the system designing is evaluated.

Energy Cost Minimization and Operation Scheduling of Stand-alone Hybrid Energy System Using Control Strategies

Energy Cost Minimization and Operation Scheduling of Stand-alone Hybrid Energy System Using Control Strategies

Techno-economic assessment of a hybrid system for energy supply in the affected areas by natural disasters: A case study

Natural disasters are considered as severe humankind’s challenges, which would make a large number of people homeless. Hence, it is vital to provide people with temporary shelters, energy, and freshwater. The purpose of this article is to find the most reliable and economical way to supply energy and water for the residential and health care containers in the different climatic conditions of Iran. Accordingly, a stand-alone hybrid energy system, including solar panels, small wind turbines, fuel generators, and battery banks is taken into consideration. The main objective of this research is to estimate the impact of various parameters such as the project lifetime, dispatch strategies for hybrid system control, and salvage on the optimum system. In addition, a sensitivity analysis regarding the economic and climatic parameters is performed to generalize the results for other areas. The results show that the cycle charging strategy is an appropriate controlling method for a hybrid system, especially for the short-term projects, in which the salvage value causes a high economic uncertainty. In addition, the study indicates that, due to the uniform power generation profile and the affordable cost of energy ranging from 0.130 $/kWh to 0.167 $/kWh, the hybrid system could be practically attainable. For the long-term project, the optimal renewable fraction is between 31.9% and 55.2%; while, for the short-term project, this value is between 12.5% and 21.4%. In the optimum dispatch strategy, for the project lifetime between 4 and 20 years, the impact of salvage on the final cost of the system would vary from 30% to 3%. These results highlight the importance of the salvage parameter in the economic viability of renewable systems.

Improved MPPT controls for a standalone PV/wind/battery hybrid energy system

In this paper, we present the modeling, optimization and control of a standalone hybrid energy system combining the photovoltaic and wind renewable energy sources to supply a dc electrical load, with storage batteries as a backup source. With the aim of improving the energy performance of the proposed system, we developed an MPPT controller based on new hybrid and robust approaches to evolve the power quality produced by both PV and Wind subsystems. For the PV subsystem, the proposed approach is based on the methods perturb and observe (P&O), sliding mode control (SMC) and fuzzy logic control (FLC). For the Wind subsystem, the proposed technique is based on the hill climbing search algorithm (HCS) and the fuzzy logic control. Also, to evaluate the efficiency of the developed controls and to analyze the behavior of each system during their maximum power point tracking, a comparison study was carried out with conventional techniques and the simulations are performed under varying weather conditions. The simulations results show the good performance of the proposed MPPT controls compared to other methods with better response time, a higher optimal power point and negligible oscillations.

Performance analysis of a stand-alone hybrid energy system for desalination unit in Egypt

Renewable energy sources are economical systems suitable for seawater treatment systems wherever there is no electrical grid. This research focuses on finding the best performance of several combinations of these resources (off-grid). The performance compares two alternatives; the first consists of a photovoltaic solar panel, wind turbine, diesel generator, and battery. The second alternative consists of a photovoltaic solar panel, hydrokinetic turbine, diesel generator, and battery. All alternatives are used to drive a small desalination unit with a capacity of 1 m3/h. HOMER software is used to optimize the hybrid renewable energy system and perform techno-economic analyses. The optimum case from the first alternative combinations consists of a wind turbine with a rated power of 10 kW, diesel generator with a rated power of 4.90 kW, and 20 kW photovoltaic solar panel. This case achieves the minimum electrical power cost of 0.2252 $/kWh and the corresponding minimum water cost of 1.10$/m3. The optimum case from the second alternative combinations consists of a hydrokinetic turbine with a maximum power of 5 kW, diesel generator with a rated power of 4.90 kW, and 2.82 kW photovoltaic solar panel. This case achieves the minimum electrical power cost of 0.1216 $/kWh and the corresponding minimum water cost of 0.56 $/m3.

Feasibility study and economic analysis of stand-alone hybrid energy system for southern Ghana

Ghana is endowed with lot of potentials in the renewable energy sector which are yet to be fully exploited. This research evaluated the techno-economic potentials of PV-Wind-DG-Battery and Wind-DG- Battery hybrid power plants in the southern part of Ghana in a town call Mankwadze to ascertain the bankability of the two systems for large-scale commercial electricity generation. The levelized cost of energy (LCOE) and net present cost (NPC) metrics were used in the economic analysis of the modelled power plants. The LCOE and NPC of the two systems were estimated at 0.382 $/kWh and $8,649,054 for the PV-Wind-DG-Battery system, respectively, whiles the Wind-DG-Battery system also recorded 0.396 $/kWh and $8,966,700 for the LCOE and NPC, respectively. The base case (generator) recorded an LCOE of 0.412 $/kWh and an OC of $345,998 with an initial cost of $454,256. The obtained results are all relatively higher than the current cost of energy for household consumers in Ghana, but a sensitivity analysis showed that the LCOEs can be reduced when certain parameters such as cost of fuel, discount and inflation rates are varied. This suggests that such projects can be done when the necessary investment climate is created by those in authority.

Cost Optimization of a Stand-Alone Hybrid Energy System with Fuel Cell and PV

Renewable energy has become very popular in recent years. The amount of renewable generation has increased in both grid-connected and stand-alone systems. This is because it can provide clean energy in a cost-effective and environmentally friendly fashion. Among all varieties, photovoltaic (PV) is the ultimate rising star. Integration of other technologies with solar is enhancing the efficiency and reliability of the system. In this paper a fuel cell–solar photovoltaic (FC-PV)-based hybrid energy system has been proposed to meet the electrical load demand of a small community center in India. The system is developed with PV panels, fuel cell, an electrolyzer and hydrogen storage tank. Detailed mathematical modeling of this system as well as its operation algorithm have been presented. Furthermore, cost optimization has been performed to determine ratings of PV and Hydrogen system components. The objective is to minimize the levelized cost of electricity (LCOE) of this standalone system. This optimization is performed in HOMER software as well as another tool using an artificial bee colony (ABC). The results obtained by both methods have been compared in terms of cost effectiveness. It is evident from the results that for a 68 MWh/yr of electricity demand is met by the 129 kW Solar PV, 15 kW Fuel cell along with a 34 kW electrolyzer and a 20 kg hydrogen tank with a LPSP of 0.053%. The LCOE is found to be in 0.228 $/kWh. Results also show that use of more sophisticated algorithms such as ABC yields more optimized solutions than package programs, such as HOMER. Finally, operational details for FC-PV hybrid system using IEC 61850 inter-operable communication is presented. IEC 61850 information models for FC, electrolyzer, hydrogen tank were developed and relevent IEC 61850 message exchanges for energy management in FC-PV hybrid system are demonstrated.

Comparative analysis of different hybrid energy system for sustainable power supply: A case study

Hybrid Power System (HPS) is an energy system with combination of different regenerative energy sources like Solar, Wind, Geo-Thermal, Biomass and several others to achieve energy sustainability. This paper investigates the feasibility of grid connected and stand-alone hybrid energy system to meet electric load requirement of a community or organization, by utilizing the available resources. Potentiality of different energy sources like solar, wind, bio-gas, etc. along with currently used energy sources is studied thoroughly by taking a case study of Kathmandu University central campus, located at Dhulikhel, Nepal. Technical and economic analysis of on-grid and off-grid hybrid system is performed to get optimum model that supply continuous energy to the end user. Furthermore, the possibility of net metering with national utility has been analysed. The main objective of this study is to identify the suitable energy mixed model, that provide the sustainable energy supply to the university, and recommend the possible energy generators to be added for fulfilling the continuously increasing load demand. The load profile of several years of the University is taken into consideration for forecasting the power demand. The findings of the research show that system when adopted to hybrid system can meet up to 55% of the load by renewable resources. Maximum renewable fraction is found to be 0.603 and maximum renewable penetration of 812%.

Optimal Combination and Sizing of a Stand–Alone Hybrid Energy System Using a Nomadic People Optimizer

In this work, the main objective is the provision of an electric supply to a residential complex located in a remote area in Iraq (Thi-Qar) that has no access to the electricity grid. This study relied on the Nomadic People Optimizer (NPO) for the tri-objective design of a stand-alone hybrid energy system (HES). The NPO algorithm comprises five main operators; these are the initial meeting, the semicircular tents distribution, the families searching, the transition of leadership, and the periodic meeting of the normal leaders. A HES optimized the electricity supply of a residential complex with 30 houses in Thi-Qar, which is located in southern Iraq at latitude 31.06 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> and longitude 46.26 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup> . The objectives of this study are to minimize the total life cycle cost (LCCT), total dump energy (DE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Total</sub> ), and total CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> emissions (E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CO2</sub> T) for 25 years. The deployed algorithm was used to evaluate six different power source scenarios (PV/battery, wind turbine/battery, 20-split diesel generators, a single large diesel generator, and PV/wind turbine/diesel generator/battery) when diesel a generator covers a deficit of renewable energy sources (RESs) without charges to the batteries, and PV/wind turbine/diesel generator and battery when a diesel generator covers a deficit in the renewable energy sources (RESs) with charges to the batteries. The data used in this study, such as the wind speed, solar radiation, and temperature, were collected from weather forecasts in Thi-Qar every hour for a full year; the data load was collected from the Thi-Qar Electricity Distribution Directorate for the same housing complex and the same number of houses in an area equipped with electricity. Additionally, the prices of the system components, maintenance, and cost of fuel were collected from the Iraq market. From the obtained results, the PV/wind/large diesel generator/battery system when the diesel generator charges the batteries was found to be the most attractive scenario because it achieved a total life cycle cost (LCCT($)) of 1.6974×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> , cost of energy (COE($/kWh)) of 0.080495746, total dump energy (DE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Total</sub> (GWh)) of (3.5418), and total CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> emission (E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CO2</sub> T (kg) of 2.957 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> .

Fractional Order PID Controller for DC Link Voltage Regulation in Hybrid System Including Wind Turbine- and Battery Packs- Experimental Validation

This paper presents a fractional order PID (FOPID) to control the operation of a stand-alone hybrid energy system with a wind turbine based on permanent magnet synchronous generator (PMSG) and a battery bank. In order to maintain the DC-link voltage at its reference value, regardless the variation in wind speed and load impedance a FOPID controller using a DC-DC buck-boost converter fed by a lead acid battery bank is used. The line to line AC output voltage regulation based on PID controller to supply RL load with constant amplitude and frequency has been achieved. The proposed FOPID controller is examined through simulation using MATLAB-simulink and experimentally via an experimental test bench under step change variation of wind speed and load impedance. The obtained simulation and experimental results using FOPID controller show better performances than the conventional PID regulator in terms of less settling time and lower overshoot in the transient state as well as a minimum steady state oscillation.

Integration of hydrokinetic turbine-PV-battery standalone system for tropical climate condition

Hydrokinetic turbine (HKT) generates electricity from the kinetic energy of flowing water and is suitable for energizing remote communities living in the proximity of rivers or canals. In this paper, a procedure for sizing components of a standalone hybrid energy system involving hydrokinetic turbine, photovoltaic and battery storage system is explained. Appropriate choices of optimum number and size of HKT modules, PV array capacity and minimum storage requirement are essential for the success of HKT-PV-battery system. The hydrokinetic turbine is modelled as a Savonius turbine and the performance parameters are established using ANSYS. Determination of the system design space is explained with an illustrative example, based on a time series simulation of the entire system. The sizing curve of the hybrid system is generated by plotting the PV array rating vs storage capacity diagram for a specified number of HKT modules. A parametric study of hydrokinetic turbine is conducted to generate a set of sizing curves and the best system configuration is identified.

Developing and evaluating a stand-alone hybrid energy system for Rohingya refugee community in Bangladesh

In this study, a hybrid system for potential electricity generation for Rohingya refugees in Kutupalong camp, Ukhia, Cox’s Bazar, Bangladesh is investigated. Six scenarios are considered, and an optimal configuration is chosen based on low cost of energy and low emission. The optimum system consists of a combination of Generator/PV Panel/Wind/Converter/Battery. The configuration has cost of energy of 0.35$ per kW, and the renewable fraction is found to be 87%. The proposed system is also environmentally friendly and the optimum system discharges less than 65%, 84%, and 61% emission when compared with grid, diesel, and kerosene respectively. From sustainability indicators, it was observed that the amount of diesel needed to be imported is 30%. Therefore, dependency on import is less, and this makes the proposed system highly reliable. Besides, this system does not use biomass to generate electricity. 87% resources come from renewable energy sources. So this system is highly sustainable. There is literally no idle time for equipment since their deployment is according to the demands of people. This idle time of equipment causes depreciation which in turn leads to less efficiency and higher cost.

Implementation of repowering optimization for an existing photovoltaic‐pumped hydro storage hybrid system: A case study in Sichuan, China

For a remote area or an isolated island, where the grid has not extended, a standalone hybrid energy system can provide cheap and adequate power for local users. However, with the development of society, the load demand will increase and the original system cannot completely meet the load demand. This situation occurs in Xiaojin, Sichuan, China. The existing photovoltaic-pumped hydro storage (PV-PHS) hybrid system in this area as the original system cannot completely meet the load requirements at present. The term “repowering” aims to maximize the reliability of power supply and the utilization of the PV-PHS hybrid energy system that differs from traditional planning optimization to build all components. The repowering strategy is to integrate wind turbines (WTs) and battery into the original system. For the repowering system, a power management strategy is proposed to determine the operating modes of the PHS and battery. Three objectives, which are minimizing percentage of the demand not supplied, levelized cost of energy, and curtailment rate of renewable energy, are considered in the optimization model. Simulation is conducted by single-objective, biobjective, and triobjective particle swarm optimization (PSO) techniques. For the single-objective optimization, the comparison of PSO and genetic algorithm (GA) is made. For the double-objective optimization, multiobjective PSO (MOPSO) is compared with weighted sum approach (WSA), and fuzzy satisfying method is utilized to find the win-win solution. The results reveal that the repowering strategy can help to achieve maximum reliability of power supply after load demand increases significantly, and the battery plays an important role in such a hybrid system.

Techno-economic feasibility of a standalone hybrid energy system for semi equatorial climates: a case study

ABSTRACTGrowing population, increasing energy demand and environmental issues such as global warming and air pollution have prompted energy officials to shift toward renewable resources particularly wind and solar. In this study, the feasibility of a hybrid energy system for electrification of a residential building located in Kish Island, Iran is assessed. The building has 10 stories, a lobby and a parking garage. Initially, the building loads that include electrical, heating, cooling, and lighting are calculated by EnergyPlus software. Then, HOMER software is employed to optimize the system configuration. The average building load and the peak power are found to be 2.2 MWh/day and 206 kW, respectively. Three optimal systems that include wind-generator, PV-generator and PV-wind-generator were proposed. The wind-gas generator system was found to have the most economic configuration while the PV-wind-generator system has more reliable performance. While the wind-generator-battery system with NPC and COE of 2,967,316 $ and 0.187$/kWh is the most cost-efficient system, the PV-wind-generator-battery system that consists of a 200 kW PV array, three wind turbines, 86 batteries, a 150 kW gas generator, and a 90 kW converter can significantly reduce the pollutants.

ACO and CS‐based hybrid optimisation method for optimum sizing of the SHES

This study proposes an efficient novel approach for achieving optimal economic operation of a standalone hybrid energy system (SHES). Optimal economic operation is obtained through a balance between power outages, carbon emission footprint left by non-renewable resources and cost per unit of energy production of renewable energy resources. SHES with battery and without battery has been considered as two different strategies to examine the impact of the energy storage element. The resulting multi-objective function is optimised using a novel combination of ant colony optimisation (ACO) and cuckoo search (CS) algorithms. The proposed hybrid algorithm is verified against a set of well-known benchmark functions and the results are compared with ACO and CS optimisation techniques. To validate the performance of the proposed algorithm, simulations have been carried out using hourly meteorological data and load data for both strategies (without and with energy storage elements) called as strategies 1 and 2, respectively. It has been observed that strategy 2 exhibits superior performance. Comparative performance analysis of the proposed technique with ACO and CS technique has been analysed and better results have been exhibited with the proposed ACO-CS algorithm. Besides the system with energy storage element yields lesser cost.