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.

Power management in co-phase traction power supply system with super capacitor energy storage for electrified railways

Increasing railway traffic and energy utilization issues prompt electrified railway systems to be more economical,efficient and sustainable.As regenerative braking energy in railway systems has huge potential for optimized utilization,a lot of research has been focusing on how to use the energy efficiently and gain sustainable benefits.The energy storage system is an alternative because it not only deals with regenerative braking energy but also smooths drastic fluctuation of load power profile and optimizes energy management.In this work,we propose a co-phase traction power supply system with super capacitor(CSS_SC)for the purpose of realizing the function of energy management and power quality management in electrified railways.Besides,the coordinated control strategy is presented to match four working modes,including traction,regenerative braking,peak shaving and valley filling.A corresponding simulation model is built in MATLAB/Simulink to verify the feasibility of the proposed system under dynamic working conditions.The results demonstrate that CSS_SC is flexible to deal with four different working conditions and can realize energy saving within the allowable voltage unbalance of 0.008%in simulation in contrast to 1.3%of the standard limit.With such a control strategy,the performance of super capacitor is controlled to comply with efficiency and safety constraints.Finally,a case study demonstrates the improvement in power fluctuation with the valley-to-peak ratio reduced by 20.3%and the daily load factor increased by 17.9%.

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.

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。

High-temperature Thermal Properties and Wear Behavior of Basalt as Heat Storage Material for Concentrated Solar Power Plants

The microstructures,components,thermal stability,specific heat capacity and thermal conductivity of basalt sample were studied.Besides,as a comprehensive result of thermal expansion and contraction process,both the friction coefficient and wear rate of the basalt sample were also characterized.Our results indicate that basalt is an excellent candidate to be used as thermal energy storage material for concentrated solar power plants,and also provide a strategy for solar energy utilization in volcanic area with excellent geographical environment.

Energy and Exergy Analysis of a New Small Concentrating Solar Power Plant

A new small concentrating solar power plant which is suitable for urban area is presented, and a theoretical framework for the energy and exergy analysis in the overall power plant is also constructed. The framework can be used to evaluate the energy and exergy losses in each component. Furthermore, the energy and exergy efficiencies have also been computed and compared for the individual components as well as for the overall plant.

Performance Analysis of Multi-Energy Hybrid System Based on Molten Salt Energy Storage

This paper briefly summarizes the current status of typical solar thermal power plant system,including system composition,thermal energy storage medium and performance.The thermo-physical properties of the storage medium are some of the most important factors that affect overall efficiency of the system,because some renewable energy sources such as solar and wind are unpredictable.A thermal storage system is therefore necessary to store energy for continuous usage.Based on the form of storage or the mode of system connection,heat exchangers of a thermal storage system can produce different temperature ranges of heat transfer fluid to realize energy cascade utilization.Founded upon the review,a small hybrid energy system with a molten-salt energy storage system is proposed to solve the problems of heating,cooling,and electricity consumption of a 1000 m2 training hall at school.The system uses molten-salt storage tank,water tank and steam generator to change the temperature of heat transfer fluid,in order to realize thermal energy cascade utilization.Compared to the existing heating and cooling system,the proposed system needs more renewable energy and less municipal energy to achieve the same results according to simulation analysis.Furthermore,by improving the original heating and cooling system,PMV has been improved.The comprehensive efficiency of solar energy utilization has been increased to 83%.

Increasing Coal-Fired Power Plant Operational Flexibility by Integrating Solar Thermal Energy and Compressed Air Energy Storage System

This paper proposed a novel integrated system with solar energy,thermal energy storage(TES),coal-fired power plant(CFPP),and compressed air energy storage(CAES)system to improve the operational flexibility of the CFPP.A portion of the solar energy is adopted for preheating the boiler’s feedwater,and another portion is stored in the TES for the CAES discharging process.Condensate water from the CFPP condenser is used for cooling compressed air during the CAES charging process.The thermodynamic performance of the integrated system under different load conditions is studied.The system operations in a typical day are simulated with EBSILON software.The system enables daily coal saving of 9.88 t and reduces CO_(2)emission by 27.95 t compared with the original CFPP at 100%load.Under partial load conditions,the system enables maximum coal saving of 10.29 t and maximum CO_(2)emission reduction of 29.11 t at 75%load.The system has maximum peak shaving depth of 9.42%under 40%load condition.The potential of the system participating ancillary service is also discussed.It is found that the integration of solar thermal system and CAES system can bring significant ancillary service revenue to a conventional CFPP.

Economic analysis of solar energy development in North Africa

The economic analysis of solar energy development is the basis of promoting the solar energy planning in north Africa and realizing the clean energy power transmission among continents. In this paper, the cost development trend of photovoltaic(PV) power and concentrating solar power(CSP) generation is analyzed, and the levelized cost of energy(LCOE) of solar power generation is forecasted. Then, taking the development of Tunisian solar energy as an example in the context of transcontinental transmission, PV power with energy storage and PV-CSP power generation are given as two kinds of development plan respectively. The installed capacity configurations of the two schemes are given with production simulation method, and comprehensive LCOE are calculated. The studies show that based on the LCOE forecast value, the LCOE of PV-CSP combined power generation will decrease when the annual utilization hours of transmission channel is increased. It can be chosen as one of important mode of the North Africa solar energy development.

Present status of pumped hydro storage operations to mitigate renewable energy fluctuations in Japan

This paper focuses on pumped hydro energy storage(PHES)plants’current operations after electricity system reforms and variable renewable energy(VRE)installations in Japan.PHES plants have historically been developed to create electricity demand at night in order to operate base load power plants,such as nuclear power plants,in stable conditions.Therefore,many PHES plants are located midway between nuclear power plants and large demand areas.However,all nuclear power plants had to–at least temporarily–shut down after the Great East Japan Earthquake followed by a nuclear accident at Fukushima Daiichi in 2011,and renewable energy power plants have been deployed rapidly after the introduction of a feed-in-tariff(FIT)scheme.Therefore,PHES plants are being used to mitigate fluctuations of VRE,especially in areas where renewable energy has been significantly installed.The daily highest capacity ratio of PHES plants in Kyushu area has recorded three times higher than it in the other areas where the past operating mode is still conducted.But those operations on PHES plants are simply followed as a dispatch rule of the Organization for Crossregional Coordination of Transmission Operators(OCCTO),market-based operations have not been conducted enough yet.The market design shall be changed to harmonize VRE installation and PHES plants’operations are necessary to make the transition from the past operating mode of PHES plants across Japan.

Hybrid Power System Options for Off-Grid Rural Electrification in Northern Kenya

For domestic consumers in the rural areas of northern Kenya, as in other developing countries, the typical source of electrical supply is diesel generators. However, diesel generators are associated with both CO2 emissions, which adversely affect the environment and increase diesel fuel prices, which inflate the prices of consumer goods. The Kenya government has taken steps towards addressing this issue by proposing The Hybrid Mini-Grid Project, which involves the installation of 3 MW of wind and solar energy systems in facilities with existing diesel generators. However, this project has not yet been implemented. As a contribution to this effort, this study proposes, simulates and analyzes five different configurations of hybrid energy systems incorporating wind energy, solar energy and battery storage to replace the stand-alone diesel power systems servicing six remote villages in northern Kenya. If implemented, the systems proposed here would reduce Kenya’s dependency on diesel fuel, leading to reductions in its carbon footprint. This analysis confirms the feasibility of these hybrid systems with many configurations being profitable. A Multi-Attribute Trade-Off Analysis is employed to determine the best hybrid system configuration option that would reduce diesel fuel consumption and jointly minimize CO2 emissions and net present cost. This analysis determined that a wind-diesel-battery configuration consisting of two 500 kW turbines, 1200 kW diesel capacity and 95,040 Ah battery capacity is the best option to replace a 3200 kW stand-alone diesel system providing electricity to a village with a peak demand of 839 kW. It has the potential to reduce diesel fuel consumption and CO2 emissions by up to 98.8%.

Optimal Design of Grid-Connected Microgrid System for Cold Chain Logistics Centre in China

The growing interest in energy conservation has inspired companies to seek alternatives to highly polluting fuel electricity generation. This study designed an optimised solar wind power generation system to fulfil the energy requirement of a cold chain logistics centre. This study first conducted a thorough analysis of the clarity indicators and daily temperature positions of the cold chain logistics centre, determined the average daily electricity demand, and proposed an effective design scheme. The energy simulation software, RETScreen 8.0, was used to determine the scale of solar photovoltaic and wind power projects that meet the expected energy needs of the cold chain logistics centre. The results indicated that the estimated annual total energy demand was 833689.2 kWh. The annual power generation of 6 kW from solar photovoltaic projects and 150 kW from wind power projects was found to be enough to meet the expected electricity demand. Solar photovoltaic power generation and wind power generation account for 2.44% and 97.56%, respectively. The hybrid energy system achieved a 96.6% reduction in carbon emissions and provides a reasonable payback period of 6.1 years and an electricity generation of 904368.674 kWh per year. The feasibility of the project and the calculated period of investment return are very reasonable. Therefore, this hybrid renewable energy system provides reliable power by combining energy sources.

计及光伏和储能接入的牵引供电系统能量管理策略

近年来,为实现电气化铁路“双碳”目标,多项铁路用能优化举措投入实施并取得一定成效,然而,单靠能耗优化治标不治本。为根治电气化铁路碳排放问题,在保证系统稳定运行的基础上,基于智能电网理念,提出计及光伏和储能接入的牵引供电系统能量管理策略。首先,构建计及光伏和储能接入的牵引供电系统;然后,基于电力市场电价及新能源出力,采用日前联合调控、日内滚动调节和实时优化控制铁路用能,并通过分层分级优化,打破各“源”端相对独立、各自为政的壁垒,实现多能互补;最后,通过共享储能模式,降低储能装置闲置率并提高新能源利用率。仿真结果表明,该能量管理策略可在保障系统运行稳定和安全的基础上有效地降低系统的运行成本,同时保持良好的电能质量。

基于模型-数据联合的光伏-光热系统储能量预测

提出一种模型-数据联合预测方法,通过机理分析建立对象动态模型,并引入未来太阳辐射强度、用户负荷预测数据进行即时模型预测,通过注意力机制改进的卷积-长短时记忆混合神经网络建立数据预测模型,并引入历史数据进行滚动数据预测,然后利用卡尔曼滤波器对2种预测模型的输出结果进行融合,实现储能量的联合预测。结果表明:联合预测兼具2种方法的优势,能很好地解决储能量预测误差随时间累积的问题,并能够及时表征气象因素突变和系统运行方式改变时储能量的变化情况,在各种天气状况下均具有良好的预测精度。

计及光伏和储能接入的牵引供电系统日前调度

近年来,为实现电气化铁路“双碳”目标,多项铁路用能优化举措投入实施,但收效甚微.为进一步降低电气化铁路碳排放,改变其供能结构,将光伏和储能装置接入牵引供电系统.首先,构建复合牵引供电系统,并根据系统供能组成将其工况分类;其次,基于系统运行约束的轻重缓急设定优先级,并通过分层分级优化,实现不同运行工况下的系统最优状态;最后,通过合理优化变流器容量,实现系统运行性能和经济效益双赢下的最小碳排放.仿真结果表明,复合牵引供电系统保障系统稳定运行的同时,也大幅降低系统碳排放并实现性能最优.

风光互补发电系统混合储能系统容量优化方法研究

风光互补发电系统受风光资源影响发电功率波动较大,配置适当的储能系统可提高新能源发电的消纳能力和电能质量。针对风光互补发电系统储能容量优化配置问题,将运行投入成本作为优化目标,提出以抽水蓄能为基础,蓄电池和超级电容参与的混合储能系统模型。该储能模型以跟踪负荷曲线作为平抑目标函数,利用集合经验模态分解和滑动平均法,对抽水蓄能机组、蓄电池和超级电容设备进行功率分配。建立了风光发电系统模型,利用带免疫的粒子群算法对储能配置容量进行寻优求解。计算结果表明,所提基于抽水蓄能的混合储能容量优化模型,对发电系统输出功率波动情况改善明显,电能消纳能力和运行经济性有所提高。

超导储能电感用于重接型电磁推进电源的研究

为了验证高温超导储能电感作为重接型电磁推进脉冲电源的可行性,采用Ansoft Maxwell 3D建立了重接型电磁推进器瞬态仿真模型,脉冲电源的设计结合了多模块储能电感串联充电和并联放电的模式,电路中采用转换电容器限制断路开关工作过程中的高电压。电感和电容参数都对最佳触发放电位置有一定的影响,即对驱动线圈电流脉冲的上升沿时间有影响。因为驱动线圈建立磁场的速度决定抛体感应出的涡流大小,抛体受到的驱动力与驱动线圈磁场大小和磁场建立的速度都有关。在多级推进系统的参数设计时,除了减小触发放电位置外,还需适当地减小驱动线圈的电感和减小转换电容的参数。

新能源发电接入下储能系统双层优化模型

针对风力发电、光伏发电等可再生分布式电源接入电网带来的网损增加、电能质量降低等问题,提出了一种风光接入下储能系统的双层优化模型.综合考虑储能规划和运行两个方面的耦合效应,上层模型考虑储能规划,以储能配置的位置和容量为决策变量,以储能系统规划成本为目标函数,下层考虑储能系统运行时电网的经济性和稳定性,以储能系统每一时刻(时间刻度为1 h)的出力为决策变量,以电网脆弱性、有功网损、购电成本为目标函数.采用改进鲸鱼算法与YALMIP+CPLEX联合方法在MATLAB中进行求解,选取改进后的IEEE33节点系统进行仿真验证,结果验证了所提模型的合理性,对比不同的场景与结果得到储能的最优配置方案与运行策略.

导通时延抖动对无电抗器电容型脉冲电源的影响

无电抗器电容储能型电源技术是提升高功率脉冲电源小型化与轻量化水平的有效途径之一,可加速推动电磁轨道发射技术的工程化应用。该型电源工作期间,晶闸管导通时延抖动是影响电源系统安全运行的重要因素。该文建立大功率晶闸管与动态负载的子电路模型,并通过模拟试验验证模型的准确性,结合系统输出性能与半导体开关性能进行对比分析,研究先导通模块的抖动阈值,为电源设计提供参考。结果表明:去除脉冲电抗器后,系统效率提升2.13%,导通时延抖动对系统输出性能影响极小;当出膛速度一致时,更高的系统效率使得无电抗器电源的小型化、轻量化水平进一步提升,体积减小了23.1%,质量减少了18.9%;导通时延抖动影响先导通模块晶闸管的运行安全,应关注高电流上升率以及由此可能引起的电流尖峰;在0.1μs的抖动阈值内,提高导通模块数可有效降低先导通模块的电流上升率;以晶闸管电流上升率限值为边界条件,导通模块数随导通时延抖动的增大以幂函数形式增加。根据系统性能分析,该型电源在增强型电磁轨道发射系统中具备工程可行性。