KnowledgeMapping of Hybrid Solar PV andWind Energy Standalone Systems: A Bibliometric Analysis

Renewable energy is becoming more attractive as traditional fossil fuels are rapidly depleted and expensive,and their use would release pollutants.Power systems that use both wind and solar energy are more reliable and efficient than those that utilize only one energy.Hybrid renewable energy systems(HRES)are viable for remote areas operating in standalone mode.This paper aims to present the state-of-the-art research on off-grid solar-wind hybrid energy systems over the last two decades.More than 1500 published articles extracted from the Web of Science are analyzed by bibliometric methods and processed by CiteSpace to present the results with figures and tables.Productive countries and highly cited authors are identified,and hot topics with hotspot articles are shown in landscape and timeline views.Emerging trends and new developments related to techno-economic analysis and microgrids,as well as the application of HOMER software,are predicted based on the analysis of citation bursts.Furthermore,the opportunities of hybrid energy systems for sustainable development are discussed,and challenges and possible solutions are proposed.The study of this paper provides researchers with a comprehensive understanding and intuitive representation of standalone solar-wind hybrid energy systems.

Solar and wind energy potential assessment for Razavi Khorasan Province in Iran

This study aims to evaluate the solar and wind energy potential across Razavi Khorasan Province,Iran,with a specific focus on the Khaf region.A preliminary assessment of mean solar radiation,mean wind speeds,and Weibull distribution parameters was conducted for different towns and zones within the province.The findings showed that Khaf has favorable characteristics for further analysis.The solar and wind energy metrics examined include global horizontal irradiance,clearness index,wind rose patterns,and turbulence intensity.At a height of 40 m,Khaf’s wind power density reached 1650 W/m^(2),indicating exceptional wind energy generation potential.Additionally,Khaf received an average annual solar radiation of 2046 kW·h/m^(2),representing significant solar energy potential.Harnessing these substantial renewable resources in Khaf could allow Razavi Khorasan Province to reduce reliance on fossil fuels,improve energy sustainability,and mitigate climate change impacts.This research contributes an in-depth assessment of Razavi Khorasan's solar and wind energy potential,particularly for the promising Khaf region.Further work may examine optimal sites for renewable energy projects and grid integration strategies to leverage these resources.

Vertically aligned montmorillonite aerogel-encapsulated polyethylene glycol with directional heat transfer paths for efficient solar thermal energy harvesting and storage

The conversion and storage of photothermal energy using phase change materials(PCMs)represent an optimal approach for harnessing clean and sustainable solar energy.Herein,we encapsulated polyethylene glycol(PEG)in montmorillonite aerogels(3D-Mt)through vacuum impregnation to prepare 3D-Mt/PEG composite PCMs.When used as a support matrix,3D-Mt can effectively prevent PEG leakage and act as a flame-retardant barrier to reduce the flammability of PEG.Simultaneously,3D-Mt/PEG demonstrates outstanding shape retention,increased thermal energy storage density,and commendable thermal and chemical stability.The phase transition enthalpy of 3D-Mt/PEG can reach 167.53 J/g and remains stable even after 50 heating-cooling cycles.Furthermore,the vertical sheet-like structure of 3D-Mt establishes directional heat transport channels,facilitating efficient phonon transfer.This configuration results in highly anisotropic thermal conductivities that ensure swift thermal responses and efficient heat conduction.This study addresses the shortcomings of PCMs,including the issues of leakage and inadequate flame retardancy.It achieves the development and design of 3D-Mt/PEG with ultrahigh strength,superior flame retardancy,and directional heat transfer.Therefore,this work offers a design strategy for the preparation of high-performance composite PCMs.The 3D-Mt/PEG with vertically aligned and well-ordered array structure developed in this research shows great potential for thermal management and photothermal conversion applications.

Research on Operation Optimization of Heating System Based on Electric Storage Coupled Solar Energy and Air Source Heat Pump

For heating systems based on electricity storage coupled with solar energy and an air source heat pump(ECSA),choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency.In this paper,four cities in three climatic regions in China were selected,namely Nanjing in the hot summer and cold winter region,Tianjin in the cold region,Shenyang and Harbin in the severe cold winter region.The levelized cost of heat(LCOH)was used as the economic evaluation index,and the energy consumption and emissions of different pollutants were analyzed.TRNSYS software was used to simulate and analyze the system performance.The Hooke-Jeeves optimization algorithm and GenOpt software were used to optimize the system parameters.The results showed that ECSA systemhad an excellent operation effect in cold region and hot summer and cold winter region.Compared with ECS system,the systemenergy consumption,and the emission of different pollutants of ECSA system can be reduced by a maximum of 1.37 times.In cold region,the initial investment in an air source heat pump is higher due to the lower ambient temperature,resulting in an increase in the LOCH value of ECSA system.After the LOCH value of ECSA system in each region was optimized,the heating cost of the system was reduced,but also resulted in an increase in energy consumption and the emission of different pollutant gases.

Investigating Load Regulation Characteristics of a Wind-PV-Coal Storage Multi-Power Generation System

There is a growing need to explore the potential of coal-fired power plants(CFPPs)to enhance the utilization rate of wind power(wind)and photovoltaic power(PV)in the green energy field.This study developed a load regulation model for a multi-power generation system comprising wind,PV,and coal energy storage using realworld data.The power supply process was divided into eight fundamental load regulation scenarios,elucidating the influence of each scenario on load regulation.Within the framework of the multi-power generation system with the wind(50 MW)and PV(50 MW)alongside a CFPP(330 MW),a lithium-iron phosphate energy storage system(LIPBESS)was integrated to improve the system’s load regulation flexibility.The energy storage operation strategy was formulated based on the charging and discharging priority of the LIPBESS for each basic scenario and the charging and discharging load calculation method of LIPBESS auxiliary regulation.Through optimization using the particle swarm algorithm,the optimal capacity of LIPBESS was determined to be within the 5.24-4.88 MWh range.From an economic perspective,the LIPBESS operating with CFPP as the regulating power source was 49.1% lower in capacity compared to the renewable energy-based storage mode.

Equivalent Method of Integrated Power Generation System of Wind, Photovoltaic and Energy Storage in Power Flow Calculation and Transient Simulation

针对工程实际开展风光储联合发电系统在潮流计算和机电暂态仿真中的等值方法研究，旨在为大容量风光储联合发电系统的并网仿真分析奠定基础。将潮流计算的等值分为单元机组和集电系统2部分来研究。单元机组等值采用根据不同控制模式选取不同节点类型的方法，针对集电系统等值提出基于损耗不变原则的方法。等值模型和详细模型的算例结果表明，潮流计算等值方法具有较好的精度。在机电暂态仿真动态等值中，基于实际工程计算的最严重工况分析原则，提出运行在满出力点的单机“倍乘”等值模型，为工程计算中的风光储联合发电系统动态等值提供了一种解决方案。

An Investigation of Battery Energy Storage Aided Wind-Coal Integrated Energy System

This paper studies the feasibility of a supply-side wind-coal integrated energy system.Based on grid-side data,the load regulation model of coal-fired power and the wind-coal integrated energy system model are established.According to the simulation results,the reasons why the wind-coal combined power supply is difficult to meet the grid-side demand are revealedthrough scenario analysis.Basedon thewind-coal combinedoperation,a wind-coalstorage integrated energy system was proposed by adding lithium-iron phosphate battery energy storage system(LIPBESS)to adjust the load of the system.According to the four load adjustment scenarios of grid-side instructions of the wind-coal system,the difficulty of load adjustment in each scenario is analyzed.Based on the priority degree of LIPBESS charge/discharge in four scenarios at different time periods,the operation mode of two charges and two discharges per day was developed.Based on the independent operation level of coal-fired power,after the addition of LIPBESS(5.5 MWh),the average qualified rate of multi-power operation in March and June reached the level of independent operation of coal-fired power,while the average qualified rate of the remaining months was only 5.4%different from that of independent operation of coal-fired power.Compared with the wind storage mode,the energy storage capacity and investment cost of wind-coal-storage integrated energy system are reduced by 54.2%and 53.7%,respectively.

Reliability Assessment Considering the Coordination of Wind Power, Solar Energy and Energy Storage

风光储联合发电系统并网后必须采取策略与系统之间实现协调调度与运行才可在保证可靠性的前提下最大化利用可再生能源，但现有的可靠性评估中还缺少对大规模风光储联合发电系统协调运行的考虑。针对此问题，基于序贯蒙特卡罗仿真方法，建立了风电、光伏和储能系统的发电可靠性评估模型，并提出了新的协调调度策略。模型综合考虑了风速、太阳光辐照度、环境温度以及2种新能源发电技术的能量变换特性和储能系统的充放电约束等因素。这些模型被应用到IEEERTS79中，通过在Matlab中编制程序进行仿真计算，考察不同的协调运行策略、联合发电系统容量配置以及储能特性对于系统裕度的影响。评估结果可为联合发电系统并网规划与设计提供参考。

Wind Power Flow Optimization and Control System Based on Rapid Energy Storage

风电功率的间歇与波动致使电场容量可信度低、可调度性差；同时易引起局部电网的电压不稳、频率波动，影响了系统的电能质量及稳定性。针对此现象，将超级电容器与蓄电池组成快速储能装置，用于风电的潮流优化控制。采用三重双向直流变换电路控制储能元件间的功率流动；采用四象限交直流变换电路控制储能与电网间的能量交换。提出基于超级电容器电压低频波动抑制的功率分配方法，可显著减少蓄电池的充放次数；提出基于储能元件荷电状态的储能能量调整规则，可避免储能元件的过充和频繁深度放电，以优化其功率调节能力。实验结果表明，系统可实现2种储能元件的优势互补，能有效平滑调节风电注入电网的有功功率，并实时补偿控制风电接入点的无功功率。

Composition Modeling and Equivalence of an Integrated Power Generation System of Wind, Photovoltaic and Energy Storage Unit

利用间接组合建模的方法,在建立典型的双馈风机、光伏发电单元和储能单元的装置级机电暂态模型基础上,采用等值方法建立三者电站级的机电暂态模型,最终通过组合建模得到了风光储联合发电系统的机电暂态模型。在大型电力系统分析软件包的PSD-BPA暂态稳定程序中实现了风光储联合发电系统的仿真功能,通过典型算例和张北＂国家风光储输示范工程＂的仿真分析验证了模型的正确性,为风光储联合发电系统的并网研究提供了分析手段。

Modeling and Simulation of a Hybrid Energy Storage System for Residential Grid-Tied Solar Microgrid Systems

Present-day power conversion and conditioning systems focus on transferring energy from a single type of power source into a single type of load or energy storage system (ESS). While these systems can be optimized within their specific topology (e.g. MPPT for solar applications and BMS for batteries), the topologies are not easily adapted to accept a wide range of power flow operating conditions. With a hybrid approach to energy storage and power flow, a system can be designed to operate at its most advantageous point, given the operating conditions. Based on the load demand, the system can select the optimal power source and ESS. This paper will investigate the feasibility of combining two types of power sources (main utility grid and photovoltaics (PV)) along with two types of ESS (ultra-capacitors and batteries). The simulation results will show the impact of a hybrid ESS on a grid-tied residential microgrid system performance under various operating scenarios.

Renewable Energy: Prospects and Challenges in Bangladesh

Among expert scientists and politicians, there is increasing agreement that it is absolutely necessary to reduce the emission of greenhouse gas (GHG) to lessen the severity of climate change. Although little, renewable energy sources currently reduce GHG that are being emitted from the energy industries. According to the majority of long-term energy estimates, renewable energy will be a substantial addition to the supply of energy worldwide by the end of this century, as capacity of renewable energy is gradually increasing in the early decades. However, developing nations like Bangladesh are largely reliant on pricey imported energy supplies (coal, gas, and oil) that lay a heavy weight on the country’s economy. Also, air pollution growing in importance as a national and international environmental issue. Regarding the development of clean and sustainable energy, renewable energy sources seem to be among the most practical and efficient alternatives, in both Bangladesh and globally. The geographic advantages of Bangladesh allow for widespread usage of the majority of such renewable energy sources. The comparative potential and use of fossil fuels against renewable energy sources globally and in Bangladesh is explored in this review.

Renewable Energy Development in OAPEC Countries: History, Current Status, and Outlook

The renewable energy industry has grown its contribution to the global energy mix, particularly in terms of electricity generation. This study investigates the implications of an increasing renewable energy share on OAPEC countries and proposes a comprehensible policy strategy for the region. Four main topics are discussed: scientific and engineering principles of renewable energy utilization, current strategies for electricity generation in each OAPEC member country, economic and environmental implications of the energy transition under two future scenarios, as well as political interactions between oil-consuming and oil-producing countries. Based on this study, realistic and cost-effective strategies are proposed for OAPEC countries to better leverage their significant renewable energy resources while stabilizing fossil fuel supplies and strengthening their position in the global energy market. To mitigate the negative impacts of the energy transition, OAPEC countries are encouraged to take the following steps: 1) Developing renewable energy in conjunction with fossil fuel resources to reduce local demand for fossil fuel and increase the supply for exportation;2) Reviewing economic policies, environmental regulations, and carbon taxes imposed by oil-consuming countries;3) Increasing investment in renewable energy infrastructure;4) Cooperating to achieve a balance between economic development and environmental protection.

An overview of the policies and models of integrated development for solar and wind power generation in China

Under the goal of “Carbon Emission Peak and Carbon Neutralization”, the integrated development between various industries and renewable energy(photovoltaic, wind power) is of great significance in China. This paper summarizes the relevant policies, integration schemes and typical cases of the integrated development between renewable energy and other industries. First, the development status of wind and solar generation in China is introduced. Second, we summarize the relevant policies issued by the National Development and Reform Commission, National Energy Administration and other departments to promote the integrated development in photovoltaic and wind power generation in China. Third, eight kinds of photovoltaic three-dimensional development models are described, including “photovoltaic + agriculture, industry, environmental protection, transportation, architecture, communication, hydrogen and ecology”. Fourth, eight kinds of wind power threedimensional development models are summarized, including “Offshore wind power + marine ranch, marine energy, marine tourism, marine oil and gas, hydrogen, communication, Energy Island” and “Onshore wind power+ courtyard”. In the future, the promotion and application of the above integrated development projects will be accelerated. This overview aims to provide reference for the design in photovoltaic and wind energy systems and help potential investors to make decisions.

Research progress on protective coatings against molten nitrate salts for thermal energy storage in concentrating solar power plants

Concentrating solar power(CSP) has garnered considerable global attention as a reliable means of generating bulk electricity, effectively addressing the intermittent nature of solar resources.The integration of molten salt technology for thermal energy storage(TES) has further contributed to the growth of CSP plants;however, the corrosive nature of molten salts poses challenges to the durability of container materials, necessitating innovative corrosion mitigation strategies.This review summarizes scientific advancements in high-temperature anticorrosion coatings for molten nitrate salts, highlighting the key challenges and future trends.It also explores various coating types, including metallic, ceramic, and carbon-based coatings, and compares different coating deposition methods.This review emphasizes the need for durable coatings that meet long-term performance requirements and regulatory limitations, with an emphasis on carbon-based coatings and emerging nanomaterials.A combination of multiple coatings is required to achieve desirable anticorrosion properties while addressing material compatibility and cost considerations.The overall goal is to advance the manufacturing, assembly, and performance of CSP systems for increased efficiency, reliability, and durability in various applications.

Complementarity Maps of Wind and Solar Energy Resources for Rio Grande do Sul, Brazil

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

A Novel Wind Energy Conversion System with Storage for Spillage Recovery

This paper proposes a new system configuration for integrating a compressed air energy storage system with a conventional wind turbine. The proposed system recycles the mechanical spillage of blades and stores it for later electricity generation with assistance from a rotary vane machine. The configuration and operational policy is explained, and a comparative case study shows that the proposed system recovers investment costs through savings on electricity procurement and revenue through power export.

Battery Energy Storage to Strengthen the Wind Generator in Integrated Power System

The wind energy generation,utilization and its grid penetration in electrical grid are increasing world-wide.The wind generated power is always fluctuating due to its time varying nature and causing stability problem.This weak interconnection of wind generating source in the electrical network affects the power quality and reliability.The localized energy storages shall compensate the fluctuating power and support to strengthen the wind generator in the power system.In this paper,it is proposed to control the voltage source inverter （VSI） in current control mode with energy storage,that is,batteries across the dc bus.The generated wind power can be extracted under varying wind speed and stored in the batteries.This energy storage maintains the stiff voltage across the dc bus of the voltage source inverter.The proposed scheme enhances the stability and reliability of the power system and maintains unity power factor.It can also be operated in stand-alone mode in the power system.The power exchange across the wind generation and the load under dynamic situation is feasible while maintaining the power quality norms at the common point of coupling.It strengthens the weak grid in the power system.This control strategy is evaluated on the test system under dynamic condition by using simulation.The results are verified by comparing the performance of controllers.

Research on Reduction of Solar Power Curtailment with Grid Connected Energy Storage System Based on Time-Series Production Simulation

Due to the variable output of renewable energy (RE) generation, difficulties of dispatching RE for power system operators could not be avoided. One of possible solutions is the energy storage technology, especially the battery storage system. The large-scale energy storage system is available to support power system reliable flexibility for load following and system frequency regulation. In this paper, the bottlenecks of large-scale solar power generation dispatching and operation in Qinghai grid are discussed, and a new PV-energy storage coordinated dispatching method is proposed for reduction of PV curtailment in Qinghai. Moreover, the validation based on the time-series production simulation is provided using real data from Qinghai. The results indicate that the proposed method can effectively decrease the curtailment of solar power and future vision of large-scale solar power coordinated operation with energy storage system is also presented.