A power plant for integrated waste energy recovery from liquid air energy storage and liquefied natural gas

Liquefied natural gas(LNG)is regarded as one of the cleanest fossil fuel and has experienced significant developments in recent years.The liquefaction process of natural gas is energy-intensive,while the regasification of LNG gives out a huge amount of waste energy since plenty of high grade cold energy(-160℃)from LNG is released to sea water directly in most cases,and also sometimes LNG is burned for regasification.On the other hand,liquid air energy storage(LAES)is an emerging energy storage technology for applications such as peak load shifting of power grids,which generates 30%-40%of compression heat(-200℃).Such heat could lead to energy waste if not recovered and used.The recovery of the compression heat is technically feasible but requires additional capital investment,which may not always be economically attractive.Therefore,we propose a power plant for recovering the waste cryogenic energy from LNG regasification and compression heat from the LAES.The challenge for such a power plant is the wide working temperature range between the low-temperature exergy source(-160℃)and heat source(-200℃).Nitrogen and argon are proposed as the working fluids to address the challenge.Thermodynamic analyses are carried out and the results show that the power plant could achieve a thermal efficiency of 27%and 19%and an exergy efficiency of 40%and 28%for nitrogen and argon,respectively.Here,with the nitrogen as working fluid undergoes a complete Brayton Cycle,while the argon based power plant goes through a combined Brayton and Rankine Cycle.Besides,the economic analysis shows that the payback period of this proposed system is only 2.2 years,utilizing the excess heat from a 5 MW/40 MWh LAES system.The findings suggest that the waste energy based power plant could be co-located with the LNG terminal and LAES plant,providing additional power output and reducing energy waste.

A study of novel real-time power balance strategy with virtual asynchronous machine control for regional integrated electric-thermal energy systems

The development of regional integrated electric-thermal energy systems(RIETES) is considered a promising direction for modern energy supply systems. These systems provide a significant potential to enhance the comprehensive utilization and efficient management of energy resources. Therein, the real-time power balance between supply and demand has emerged as one pressing concern for system stability operation. However, current methods focus more on minute-level and hour-level power optimal scheduling methods applied in RIETES. To achieve real-time power balance, this paper proposes one virtual asynchronous machine(VAM) control using heat with large inertia and electricity with fast response speed. First, the coupling timescale model is developed that considers the dynamic response time scales of both electric and thermal energy systems. Second, a real-time power balance strategy based on VAM control can be adopted to the load power variation and enhance the dynamic frequency response. Then, an adaptive inertia control method based on temperature variation is proposed, and the unified expression is further established. In addition, the small-signal stability of the proposed control strategy is validated. Finally, the effectiveness of this control strategy is confirmed through MATLAB/Simulink and HIL(Hardware-in-the-Loop) experiments.

Enhancing Wind Power Integration through Optimal Use of Flexibility in Multi-Carrier Energy Systems from the Danish Perspective

Denmark’ goal of being independent of fossil energy sources in 2050 puts forward great demands on all energy subsystems (electricity, heat, gas and transport, etc.) to be operated in a holistic manner. The Danish experience and challenges of wind power integration and the development of district heating systems are summarized in this paper. How to optimally use the cross-sectoral flexibility by intelligent control (model predictive control-based) of the key coupling components in an integrated heat and power system including electrical heat pumps in the demand side, and thermal storage applications in buildings is investigated.

Structured Microgrids (SμGs) and Flexible Electronic Large Power Transformers (FeLPTs)

Structured microgrids(SμGs)and Flexible electronic large power transformers(FeLPTs)are emerging as two essential technologies for renewable energy integration,flexible power transmission,and active control.SμGs provide the integration of renewable energy and storage to balance the energy demand and supply as needed for a given system design.FeLPT’s flexibility for processing,control,and re-configurability offers the capability for flexible transmission for effective flow control and enable SμGs connectivity while still keeping multiscale system level control.Early adaptors for combined heat and power have demonstrated significant economic benefits while reducing environmental foot prints.They bring tremendous benefits to utility companies also.With storage and active control capabilities,a 300-percent increase in bulk transmission and distribution lines are possible without having to increase capacity.SμGs and FeLPTs will also enable the utility industry to be better prepared for the emerging large increase in base load demand from electric transportation and data centers.This is a win-win-win situation for the consumer,the utilities(grid operators),and the environment.SμGs and FeLPTs provide value in power substation,energy surety,reliability,resiliency,and security.It is also shown that the initial cost associated with SμG and FeLPTs deployment can be easily offset with reduced operating cost,which in turn reduces the total life-cycle cost by 33%to 67%.

Optimal Scheduling for Flexible Regional Integrated Energy Systemwith Soft Open Point

The Regional Integrated Energy System(RIES)has brought new modes of development,utilization,conversion,storage of energy.The introduction of Soft Open Point(SOP)and the application of Power to Gas(P2G)technology will greatly deepen the coupling of the electricity-gas integrated energy system,improve the flexibility and safety of the operation of the power system,and bring a deal of benefits to the power system.On this background,an optimal dispatch model of RIES combined cold,heat,gas and electricity with SOP is proposed.Firstly,RIES architecture with SOP and P2G is designed and its mathematical model also is built.Secondly,on the basis of considering the optimal scheduling of combined cold,heat,gas and electricity,the optimal scheduling model for RIES was established.After that,the original model is transformed into a mixed-integer second-order cone programming model by using linearization and second-order cone relaxation techniques,and the CPLEX solver is invoked to solve the optimization problem.Finally,the modified IEEE 33-bus systemis used to analyze the benefits of SOP,P2G technology and lithium bromide absorption chillers in reducing systemnetwork loss and cost,as well as improving the system’s ability to absorb wind and solar and operating safety.

Prime Energy Challenges for Operating Power Plants in the GCC

There is a false notion of existing available, abundant, and long lasting fuel energy in the Gulf Cooperation Council (GCC) Countries;with continual income return from its exports. This is not true as the sustainability of this income is questionable. Energy problems started to appear, and can be intensified in coming years due to continuous growth of energy demands and consumptions. The demands already consume all produced Natural Gas (NG) in all GCC, except Qatar;and the NG is the needed fuel for Electric Power (EP) production. These countries have to import NG to run their EP plants. Fuel oil production can be locally consumed within two to three decades if the current rate of consumed energy prevails. The returns from selling the oil and natural gas are the main income to most of the GCC. While NG and oil can be used in EP plants, NG is cheaper, cleaner, and has less negative effects on the environment than fuel oil. Moreover, oil has much better usage than being burned in steam generators of steam power plants or combustion chambers of gas turbines. Introducing renewable energy or nuclear energy may be a necessity for the GCC to keep the flow of their main income from exporting oil. This paper reviews the GCC productions and consumptions of the prime energy (fuel oil and NG) and their role in electric power production. The paper shows that, NG should be the only fossil fuel used to run the power plants in the GCC. It also shows that the all GCC except Qatar, have to import NG. They should diversify the prime energy used in power plants;and consider alternative energy such as nuclear and renewable energy, (solar and wind) energy.

New Strategy of IPACS Design and Energy Management for Spacecrafts

The design problem of an integrated power and attitude control system （IPACS） for spacecrafts is investigated. A Lyapunov-typed IPACS controller is designed for a spacecraft equipped with 4 flywheels （3 orthogonal ＋ 1 skew）. This controller keeps in the nonlinear properties of original systems, so the control result can be more precise. A control law of the flywheels is also proposed to accomplish the attitude control and energy storage simultaneously. Aiming at the limitations existing in the power conversion characteristic and the wheel＇s motor, a new strategy of energy management is proposed. The strategy can not only make the charged/discharged energy reaching balance in each orbital period, but also sufficiently utilize the power provided by the solar arrays. Therefore, the size and mass of solar arrays can be decreased, and the cost of spacecraft can be economized. A simulation example illustrates the validity of the designed IPACS.

Building Integrated Photovoltaic Systems for Single Family Dwellings: Innovation Concepts

Growing consumer interest in distributed Building Integrated Photovoltaic (BIPV) Systems and industry competition to reduce installation costs are stimulating the development of deploying these materials to the residential sector of the building industry. This emerging market continues to attract the attention of many stakeholders, yet cohesive opportunities to deploy in residential sectors, specifically detached single-family dwellings, is scattered. As a result, this study of literature and implementation strategies through simple examples looks to identify several characteristics related to BIPV. Characteristics that were studied in this initial pilot study were design considerations for system selection, applicability to residential construction, and system and material options and enhancements. A case-study home was analyzed demonstrating opportunity for implementation of BIPV on an existing residence. Strategies for maximizing the energy-generating capacity of the system to achieve net-zero energy performance, including all building surfaces and landscaping were also explored. This body of work provides a state-of-the-art review on common materials as well as the more customizable types.

含碳捕集电厂与氢能多元利用的综合能源系统低碳经济调度

随着中国“碳达峰·碳中和”战略的不断推进,综合能源系统的绿色低碳转型迫在眉睫。针对传统碳捕集电厂灵活性较差、风电并网难以消纳等问题,提出一种含碳捕集电厂与氢能多元利用的综合能源系统低碳经济调度模型。首先,引入储液罐对传统碳捕集电厂进行改造,提高电厂应对风电波动的运行灵活性;其次,构建含两段式电转气、氢燃料电池、储氢罐和掺氢热电联产在内的氢能多元利用结构,以充分挖掘氢能利用与碳捕集电厂的协同运行潜力。在此基础上,引入阶梯碳交易机制,建立以碳交易、碳封存、燃煤及购气成本之和最小为优化目标的低碳经济调度模型。算例结果表明,文中模型能够有效提高系统的风电消纳水平和能源利用效率,具有显著的低碳经济效益。此外,碳交易基准价格的合理设定能够引导系统提高碳捕集水平。

储液式CCS耦合P2G的综合能源系统低碳经济调度

为应对电转气P2G(power-to-gas)和碳捕集系统CCS(carbon capture system)在可再生能源出力不足时耦合失效的问题,考虑对常规CCS引入CO_(2)储液罐以加强P2G和CCS的耦合。首先,构建储液式CCS和P2G的耦合模型,利用储液罐将CCS捕集的CO_(2)时移至可再生能源富足时段,供P2G再利用;其次,构建储液式CCS与P2G耦合的电热气综合能源系统日前优化调度模型;最后,以北方某工业园区为例进行仿真。结果证明所提模型可以充分利用CCS捕集的CO_(2),从而获得更好的经济和环境效益。

基于碳捕集-电转气的矿区综合能源系统协同优化调度

“双碳”战略目标下,为促进风光消纳与能源电力低碳转型、提高矿区能源利用率,提出一种含伴生能源和碳捕集与电转气耦合的矿区综合能源系统低碳经济调度模型。首先,综合考虑瓦斯、乏风、涌水等矿区伴生能源利用,建立矿区综合能源系统基本模型,并以碳捕集和电转气设备为耦合单元,促进节能减排与可再生能源消纳。然后,引入奖惩阶梯式碳交易机制,以矿区综合能源系统运行成本最小为目标,建立矿区综合能源系统协同优化调度模型。最后,以中国云南某大型煤矿为例,通过设置不同场景进行仿真分析。结果表明,所提模型能够促进矿区综合能源系统低碳经济运行,提高风光消纳率。

考虑超碳需求响应的综合能源系统低碳优化调度

西北地区新能源发展迅速,充分利用当地独有的光热资源优势,同时结合火电低碳化改造与新能源协同运行,有利于推动当地能源系统绿色低碳转型。为尽最大限度地提升系统的减碳能力,提出一种基于源荷协同降碳的超碳需求响应模型,将动态碳排放因子作为分时电价的惩罚因子,从而将源侧碳信号传递至荷侧,驱使用户侧进行低碳性状态转移。首先,在日前调度阶段,构建预调度-再调度两阶段调度运行机制,再调度根据预调度的系统状态信息进行超碳需求响应,来深度降低系统碳排量。其次,将光热电站引入综合能源系统,与风电场、碳捕集电厂协同运行,从而构建高比例新能源场景,来验证超碳需求响应在此场景下的减碳效益。最后,建立了基于超碳需求响应的预调度-再调度两阶段低碳调度模型。经算例仿真分析表明,所提源荷协同降碳的新思路能有效提高系统的减碳能力,深入挖掘系统的降碳空间,提升系统的经济效益。

含整体煤气化燃料电池-碳捕集电厂的风火储系统分布鲁棒调度方法

整体煤气化燃料电池(integrated gasification fuel cell,IGFC)是与碳捕集技术高度适配的清洁、高效、稳定的绿色煤电技术,有望克服传统碳捕集技术在低浓度CO_(2)环境下产生的高成本、高能耗问题。该文构建含IGFC碳捕集电厂的风火储发电系统。研究IGFC碳捕集电厂的运行机理,对IGFC内部各环节建立数学模型,提出工况匹配时燃烧利用率和阴极空气利用率需要满足的运行条件,并针对该型碳捕集电厂的电碳特性进行分析。为计及风电出力的不确定性,构建风火储系统的两阶段分布鲁棒经济调度模型,引入k阶适应性理论,提出基于正交支撑子集策略的求解方法来获得鲁棒对等式。最后,在改进IEEE-30节点系统中进行算例分析,结果表明,该型碳捕集电厂可利用阳极碳富集的优势,实现系统低碳经济调度的目标,并验证所提优化方法能为可行解提供可解释性。

考虑条件风险价值和阶梯碳交易的综合能源系统优化调度

为进一步提升综合能源系统环境效益,减少新能源出力不确定性所带来的潜在风险,提出了计及条件风险价值(conditional value at risk,CVaR)以及阶梯碳交易的综合能源系统优化调度模型。考虑到系统风电和光伏出力不确定性可能带来的影响,采用条件风险价值量度不确定性带来的潜在风险,并将碳捕获技术、电转气设备以及阶梯式碳交易机制引入系统调度模型,构建了综合考虑系统运行成本和碳交易成本的优化调度目标函数,由于所建立模型为混合整数规划问题,采用CPLEX求解器进行求解,设置4种场景进行验证分析,算例表明所提模型可有效减少二氧化碳排放,在兼顾经济性和环境性的同时引入CVaR,可避免由于忽略风光不确定性所带来的较为乐观的调度结果,使系统最终调度结果更为合理。

计及氢能高效利用和热电灵活输出的综合能源系统源荷灵活运行策略

为进一步发挥氢能高效利用优势,构建绿色低碳能源系统,提出一种计及氢能高效利用和热电联产灵活输出的综合能源系统源荷灵活运行策略。首先,对源侧供能模型进行两方面改进:一是引入含风电制氢、燃气混氢、多能用氢和储氢的氢能利用模型,并考虑到电解水和甲烷化反应过程中的热量散失情况,引入热量回收装置,构建计及热量回收的氢能高效利用模型;二是针对常规热电联产灵活性不足的问题,构建含电锅炉和有机朗肯循环的热电灵活输出模型,以解耦常规热电联产“以热定电”和“以电定热”限制。其次,在荷侧引入含可转移、可削减和可平移的电、热柔性负荷,以缓解电、热负荷峰谷差,并与源侧相结合,形成源荷灵活运行模型。最后,综合考虑阶梯型碳交易成本、设备运行维护成本、弃风成本以及购能成本,建立综合能源系统源荷灵活优化运行模型。采用CPLEX求解器对所提综合能源系统源荷灵活运行模型进行求解,并设置不同场景进行对比。结果表明,相比常规氢能利用模型,考虑所提计及热量回收的氢能高效利用模型时,系统的总成本、碳排放量分别降低了1.92%、4.22%,并且引入热电联产改进模型后,其总成本、碳排放量可进一步降低4.08%、7.32%,实现系统低碳、经济和灵活运行。

“双碳”目标下我国燃煤发电转型升级发展路径

统筹推进我国燃煤发电(简称“煤电”)转型升级,推动煤电功能定位转变,是实现“双碳”目标和加快构建新型电力系统的重要任务。针对我国燃煤发电转型升级的迫切需求,该文分析当前我国煤电的装机规模及其特点,评估了煤电的能耗、灵活性和碳排放3方面的发展水平,解析我国煤电未来发展方向,重点探讨了煤电热力系统重构、煤电与储能融合、煤电与其他能源及碳捕集、利用与封存(carbon capture,utilization and storage,CCUS)的互补集成、“安全、高效、清洁、低碳、灵活”多目标协同4个方面的发展路径,提出新一代煤电高质量发展的基本思路。面向新形势下“安全、高效、清洁、低碳、灵活”的发展目标,未来我国煤电机组需要开展热力系统深度重构,通过热力系统的大范围重新设计、优化或改造,提高机组效率和灵活性、降低能耗和碳排放;可以将储热、飞轮、压缩空气等储能与煤电系统有机融合,突破煤电机组自身调节潜力约束,拓宽煤电机组的调节区间,提升机组变负荷能力和效率;充分利用煤电机组内丰富的物质流和能量流,可将煤电与其他能源或系统在多个环节匹配耦合,实现整体的多能互补能量梯级利用,提升总体能效与低碳水平;应重点从设计和运行两个维度实现多目标协同,在设计阶段注重高效清洁技术的集成与智能化、自动化,在运行过程中采用智能化、精细化控制策略。该文旨在增强煤电战略价值认知,为我国煤电转型升级提供理论参考和路径建议,助力新一代煤电在推进“双碳”进程和构建新型电力系统中发挥更广泛、更积极作用。

舰船综合电力系统研究进展与应用建议

该文概述舰船综合电力系统(integrated power system,IPS)的原理、组成、分类、特点与技术难点,介绍国内外工程研制情况,综述集成设计、大容量直流源及其并联组网控制、大容量直驱式电力推进、直流大电流开断保护、电力电子静止电源、高密度储能、智能化能量管理等7项共性技术及我国技术研究突破情况。针对IPS在民用新能源船舶、电动及混动飞机、轨道交通、海上能源高效利用等推广应用实际需求,给出系统推荐方案,并提出各应用场景下还需重点研究的内容,旨在为IPS在多领域推广应用提供参考。

水路交通系统的发展现状与未来展望

水路交通系统是以船舶等为载运工具、以港口为节点、以海洋、江河、湖泊等水域为通道的一种运输方式,能够实现货物、人员的搭载与时空位移,是综合交通体系中不可或缺的重要组成部分。本文分析了国内外水路交通系统发展现状,梳理了水路交通系统未来需求及技术特征,提出了水路交通运输规划与组织优化、绿色船舶动力系统及供给体系、人机共融船舶岸基驾控系统、海域立体综合运输系统、水路交通系统控制体系、气象导航与安全航行等未来水路交通系统发展方向,为提高水路交通系统运营效率与服务质量提供理论基础与技术参考。

含电转气和碳捕集耦合的综合能源系统多时间尺度优化调度

为提升综合能源系统(integrated energy system,IES)的可再生能源消纳以及低碳经济效益,提出含电转气(power-to-gas,P2G)和碳捕集(carbon capture system,CCS)耦合的综合能源系统多时间尺度优化调度模型。首先,建立基于阶梯型碳交易机制的含P2G和CCS耦合模型,并构建多能量转换设备和储能设备组成的电-热-冷综合能源系统;其次,基于多时间尺度的优化调度策略,以购能成本、运维成本、碳交易成本、弃风光成本为目标函数建立日前-日内滚动-实时调整3个阶段的优化调度模型;最后,以四川某工业园区为例进行仿真,结果证明本文提出的模型有效提高了综合能源系统的低碳经济效益、能源利用率和系统稳定性。

考虑电转氨和生物质废能转换的农村化工综合能源系统低碳调度方法

农村地区能源绿色转型发展是构建现代能源体系的重要组成部分,而引入化工类产业在促进乡村振兴的同时,也带来严重的污染问题。因此,研究农村化工生产脱碳及园区能源结构优化对实现“双碳”目标和农村现代化具有重要意义。该文提出一种考虑电转氨和生物质废能转换的农村化工园区综合能源系统低碳调度方法,通过利用富余可再生资源产生绿氨,考虑碳-氨耦合过程,将绿氨与碳捕集设备联合运行促进化工生产,同时利用生物质能替代燃煤发电,三者构建化工园区联合生产单元,进而降低园区碳排放及运行成本。首先,建立电转氨两阶段模型和生物质废能转换模型及其能流关系。其次,构建化工园区联合生产单元,分析其电、热、气以及碳能量耦合特性。再次,引入有机朗肯循环(organic Rankine cycle,ORC)余热发电和负荷侧综合需求响应,综合优化化工园区联合生产单元。最后,以化工园区运行总成本最低为目标,通过不同场景对比分析证明所提调度方法对化工园区有较好的改善作用,可为农村产业结构调整和能源转型提供理论支持。