Comparison of life cycle performance of distributed energy system and conventional energy system for district heating and cooling in China

The distributed energy system has achieved significant attention in respect of its application for singlebuilding cooling and heating.Researching on the life cycle environmental impact of distributed energy systems(DES)is of great significance to encourage and guide the development of DES in China.However,the environmental performance of distributed energy systems in a building cooling and heating has not yet been carefully analyzed.In this study,based on the standards of ISO14040-2006 and ISO14044-2006,a life-cycle assessment(LCA)of a DES was conducted to quantify its environmental impact and a conventional energy system(CES)was used as the benchmark.GaBi 8 software was used for the LCA.And the Centre of Environmental Science(CML)method and Eco-indicator 99(EI 99)method were used for environmental impact assessment of midpoint and endpoint levels respectively.The results indicated that the DES showed a better life-cycle performance in the usage phase compared to the CES.The life-cycle performance of the DES was better than that of the CES both at the midpoint and endpoint levels in view of the whole lifespan.It is because the CES to DES indicator ratios for acidification potential,eutrophication potential,and global warming potential are 1.5,1.5,and 1.6,respectively at the midpoint level.And about the two types of impact indicators of ecosystem quality and human health at the endpoint level,the CES and DES ratios of the other indicators are greater than1 excepting the carcinogenicity and ozone depletion indicators.The human health threat for the DES was mainly caused by energy consumption during the usage phase.A sensitivity analysis showed that the climate change and inhalable inorganic matter varied by 1.3%and 6.1%as the electricity increased by 10%.When the natural gas increased by 10%,the climate change and inhalable inorganic matter increased by 6.3%and 3.4%,respectively.The human health threat and environmental damage caused by the DES could be significantly reduced by the optimization of natural gas and electricity consumption.

Initiative Optimization Operation Strategy and Multi-objective Energy Management Method for Combined Cooling Heating and Power

This paper proposed an initiative optimization operation strategy and multi-objective energy management method for combined cooling heating and power U+0028 CCHP U+0029 with storage systems. Initially, the initiative optimization operation strategy of CCHP system in the cooling season, the heating season and the transition season was formulated. The energy management of CCHP system was optimized by the multi-objective optimization model with maximum daily energy efficiency, minimum daily carbon emissions and minimum daily operation cost based on the proposed initiative optimization operation strategy. Furthermore, the pareto optimal solution set was solved by using the niche particle swarm multi-objective optimization algorithm. Ultimately, the most satisfactory energy management scheme was obtained by using the technique for order preference by similarity to ideal solution U+0028 TOPSIS U+0029 method. A case study of CCHP system used in a hospital in the north of China validated the effectiveness of this method. The results showed that the satisfactory energy management scheme of CCHP system was obtained based on this initiative optimization operation strategy and multi-objective energy management method. The CCHP system has achieved better energy efficiency, environmental protection and economic benefits. © 2014 Chinese Association of Automation.

A Distributed Energy System with Advanced Utilization of Internal Combustion Engine Waste Heat

New trigeneration system consists of an internal combustion engine,a power and cooling cogeneration system and an absorption heat transformer system.The exhaust gas is recovered by the power and cooling cogeneration subsystem producing the cooling and power.The jacket water is recovered by the absorption heat transformer subsystem producing lowpressure steam.The exergy performance and the energy saving performance which is evaluated by the primary energy saving ratio of the new distributed energy system are analyzed.The effects of the ratio of the output power and cooling of the power and cooling cogeneration subsystem and the generator outlet temperature of the absorption heat transformer subsystem to the primary energy saving ratio are considered.The contributions of the subsystems to the primary energy saving ratio are quantified.The maximum primary energy saving ratio of the new distributed energy system is 15.8%,which is 3.9 percentage points higher than that of the conventional distributed energy system due to the cascade utilization of the waste heat from the internal combustion engine.

A multi agent-based optimal control method for combined cooling and power systems with thermal energy storage

Combined cooling,heating and power(CCHP)systems have been considered as a potential energy saving technology for buildings due to their high energy efficiency and low carbon emission.Thermal energy storage(TES)can improve the energy efficiency of CCHP systems,since they reduce the mismatch between the energy supply and demand.However,it also increases the complexity of operation optimization of CCHP systems.In this study,a multi-agent system(MAS)-based optimal control method is proposed to minimize the operation cost of CCHP systems combined with TES.Four types of agents,i.e.,coordinator agents,building agents,energy management agents and optimization agents,are implemented in the MAS to cooperate with each other.The operation optimization problem is solved by the genetic algorithm.A simulated system is utilized to validate the performance of the proposed method.Results show that the operation cost reductions of 10.0%on a typical summer day and 7.7%on a typical spring day are achieved compared with a rule-based control method.A sensitivity analysis is further performed and results show that the optimal operation cost does not change obviously when the rated capacity of TES exceeds a threshold.

计及全生命周期成本的公交光伏充电站储能优化配置方法

“双碳”目标下城市公交车全面推进电动化,公交光伏充电站面临并网点负载压力大、运营成本高的问题。提出公交光伏充电站储能优化配置方法。基于大量的调研数据分析公交充电负荷特性,构建公交光伏充电站典型运行场景;综合考虑充电站运营商利益、公共交通通勤需求以及并网点的容量限制,构建计及全生命周期成本的公交光伏充电站电池储能优化配置双层模型。以北京某在营公交充电站为算例,验证了所提配置方法的有效性,量化评估了光伏发电余量上网、公交车充电策略、电网电价及电池购置价格等因素对充电站配置储能运营经济性的影响。

基于室内非均匀环境营造的新型通风模式下人员热舒适性及系统节能潜力

为解决现有通风空调系统无法根据占用区域实现按需供冷造成的热不舒适及能源浪费问题,本研究根据人员占用区域需求实时切换气流模式组合及冷量供给,提出了一种新型通风模式,旨在利用多种气流模式的最优组合控制特定需求场景。采用数值模拟的方法探究了不同占用区域情况下新型通风模式的人员热舒适性和系统的节能潜力,并与混合通风模式和层式通风模式进行了对比。结果表明:新型通风模式在气流组织上具有明显优势;新型通风模式较混合通风模式和层式通风模式具有更高的热舒适性,空气分布特性指数最大;新型通风模式局部冷量利用系数最小,冷量有效利用率最高,所需供冷量最小,因此新型通风模式的节能潜力最大。

Water, Air Emissions, and Cost Impacts of Air-Cooled Microturbines for Combined Cooling, Heating, and Power Systems： A Case Study in the Atlanta Region

The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.

用于新能源一次调频的储能经济配置研究

新能源参与电力系统一次调频时需要解决能量来源问题,配置储能是一种有效的方式。在实际应用中储能配置需要充分考虑物理特性约束、单位成本等多方面的因素,综合比较技术经济性。但是,现有文献所提出的储能系统配置方案通常对运行场景的分析较多,对各类工程约束和储能的实际成本数据则考虑较少。基于储能的实际成本数据,在充分考虑储能系统物理特性及工程设计约束的情况下,对新能源一次调频应用场景下储能系统分布式接入场站的经济性展开了研究。分析了锂电池、飞轮和超级电容3类储能系统的技术特点和设计约束,在此基础上提出了3类储能用于一次调频的配置方法,结合配置方案进行了成本分析和技术经济性比较。

Economics of energy storage technology in active distribution networks

An economic and environmental evaluation of active distribution networks containing lithium ion batteries(Li-ion),sodium sulfur batteries(NaS)and vanadium redox flow batteries(VRB)was carried out using the EnergyPLAN software.The prioritization schemes of the combination of energy storage systems and intermittent energy systems were studied technically and economically based on some specific situations of the grid integrated with wind power.The results suggest that the technical and economic optimal intermittent energy-storage capacity ratio was 2:1 in predetermined energy system scenarios.Liion batteries storage system performed the best in critical excess electricity production(CEEP)absorption,energy saving and emission reduction while NaS batteries storage system was the most competitive among the three due to its cheaper costs.

多源分布式换能系统构建理论方法研究与应用

“双碳”背景下分布式换能系统以其在低碳环保方面的显著优势逐渐在集中供热领域得到应用。本文针对分布式换能系统中热泵、太阳能集热器、板式换热器和燃料电池等关键单元提出了单元能耗评价方法,并通过EES软件对各单元进行了热力学建模以定量评价不同单元在不同工况下的经济性,进而提出分布式换能系统的构建方法以获得流程经济性最优化。以此为依据搭建了最优化流程,并以北京地区某小区为例分析了该系统的供暖季性能,最后进行了经济性和碳减排分析。结果表明:室外温度在-10~5℃范围内变化时,该新型分布式换能系统的COP为2.69~4.43,太阳能集热器效率为45.19%~61.87%,燃料电池日发电量为8047.4~32228.0 kW·h;与常规热力站相比,该新型分布式换能系统的运行成本节省率为32.66%~53.92%,碳减排率为69.07%~73.29%。

计及经济性与可靠性的台区储能优化配置

分布式光伏装机量猛增影响了台区的安全可靠运行,台区储能成为消纳分布式光伏的关键,但台区储能项目投资的经济性与电网可靠性之间难以平衡。对此,提出一种基于台区储能反配新能源模式的综合考虑经济性与可靠性的台区储能优化配置方法。首先,建立台区储能容量优化经济模型;其次,基于台区储能经济性优化结果进行电网可靠性模拟仿真;最后,考虑经济性与可靠性等综合指标,运用优劣解距离法对各节点进行选址评估,通过累积分布曲线确定台区储能配置方案。算例仿真结果表明,文中所提方法可以有效提升配电网分布式光伏消纳能力,更好地平衡了台区储能投资的经济性与电网可靠性,相关结果可为新能源配储比例的合理设置提供借鉴。

计及配电网可靠性和运行经济性的电网侧储能优化配置

针对储能提升系统可靠性和降低运行经济性的问题,提出一种综合考虑配电网可靠性和运行经济性的两阶段储能优化配置方法。在单一主电源供电可靠性模型的基础上,分别建立含储能系统单点接入、多点接入结构下的供电可靠性模型:阶段1以储能系统单点接入拓扑下的模型为规划对象,建立多目标规划运行双层模型,上层以储能容量投资成本、系统安全成本、统一时间尺度下的运行成本之和最小为优化目标,下层以综合运行成本之和最小为优化目标,同时考虑网络损耗、电能质量、负荷波动这3种运行成本,应用Gurobi工具包求解得到储能的规划运行方案;阶段2考虑新增供电线缆改造后的储能多点接入拓扑下的模型,以可靠性提升效益最大为优化目标,得到新增线缆规划方案。以修改的IEEE 33节点系统为算例,从不同的场景验证所提方法的有效性,并分析不同的停电风险价格对规划结果的影响。

冷凝器喷雾冷却对氟泵热管复合空调的性能影响

为了降低数据中心制冷系统能耗,解决氟泵热管复合空调夏季耗电量大的问题,通过在冷凝器外侧加装喷雾冷却装置提高机组能效,并在不同工况和不同城市分别对其进行性能研究和适用性分析。结果表明:在室外温度为15、25、35℃工况下,与未安装喷雾冷却装置相比,氟泵热管复合空调的制冷消耗总功率分别从3.44、4.51、6.48 kW降低至2.81、3.66、4.89 kW,能效比(energy efficiency ratio,EER)分别提高了13.4%、27%、30.7%。进一步分析显示,在哈尔滨、北京、昆明、上海、广州五座典型城市中,全年能效比(annual energy efficiency ratio,AEER)分别提高了4.16%、6.69%、9.88%、10.76%、19.65%,并且空调的能效比提高率随着室外温度的升高而增大,在中、高温时长占比较大的城市节能效果更加显著。

某能源站新增蓄冷系统经济性分析

集中供冷系统可通过水蓄冷方式提高能源利用率,降低能源成本,是目前集中供能站节能减排的主要举措之一。以某能源站为研究对象,提出了针对该能源站集中供冷系统在分时电价下的蓄冷运行方案,并模拟蓄冷工况下的运行策略,计算目前运行策略和蓄冷运行策略下的能源成本。结果显示:该能源站新增10万RT水蓄冷系统后,实现削峰填谷负荷615.2 kWh(约72%),每年节约电费约537万元,节省电费约56%。其中蓄冷罐投资费用约3770万元,投资回报期约7年。研究表明,在分时电价机制下,通过水蓄冷系统的削峰填谷策略可以显著提高集中供冷系统的经济效益,为能源站经济运行提供参考。

工业园区分布式冷热电能源系统规划

以工业园区冷热电能源需求为例,研究天然气分布式能源站的冷、热、电三联供,有助于园区企业降低用能成本及设备运营投资。为此,在分析参阅国内外研究文献、筛选整理有效数据的基础上,归纳总结工业园区冷热电负荷预测方法,并基于典型供能装置数学模型,建立工业园区分布式冷热电能源系统规划模型,最后以武清高村科技创新园为算例,验证模型的可行性和有效性。

燃气冷热电联供技术在分布式能源中的应用与发展

随着全球能源结构的转型和可持续发展目标的提出,分布式能源系统逐渐成为了能源领域的研究热点。燃气冷热电联供技术作为分布式能源的重要组成部分,具有高效、环保、灵活等优势,在节能减排、提高能源利用效率等方面发挥着重要作用。文章介绍了燃气冷热电联供技术的基本原理和分类,分析了其在分布式能源中的应用现状,探讨了其面临的挑战和未来的发展方向,旨在为燃气冷热电联供技术在分布式能源中的推广和应用提供参考。

配套在数据中心侧的天然气分布式能源站“黑启动”逻辑分析

天然气分布式能源站配套在数据中心侧的项目,稳定可靠是其第一要求。在市电失去的情况下,能源站的“黑启动”显得至关重要,直接影响到供能系统的整体安全性。本文以配套在某数据中心侧的能源站为例,详细分析“黑启动”运行逻辑,为后期同类型项目或者小型供能站在“黑启动”逻辑搭建方面提供一些相关的思考和建议。

某区域能源项目燃气分布式能源系统经济性与运行策略分析

建筑领域的节能减排、能源结构转型是我国实现双碳目标的关键一环,多能互补耦合和高效利用的区域供能是实现城市建筑领域低碳发展的重要路径之一。天然气作为清洁优质的能源,是区域供能中能源结构调整的重要环节。燃气分布式能源系统(CCHP系统)可以充分实现能源的梯级利用,但燃气价格及电力价格等因素限制了其推广和发展。本文以某河水源热泵与CCHP系统耦合供能区域能源项目为研究对象,在湖南省现有燃气和电力价格基础上,对该项目CCHP系统不同运行策略下、不同容量的方案进行经济性比选分析,以确定最优容量和最佳运行方案,并提出CCHP系统经济性运行的气电价格比临界值,便于指导项目后续运行。

60 MW级空冷发电机电磁设计及试验验证

随着能源结构的改变,小空冷发电机市场逐渐成为行业关注的重点。文章介绍了60 MW级空冷发电机电磁设计方案,并通过型式试验验证了发电机的主要电气性能,结果符合预期,发电机整体性能优良。

基于R410A制冷剂的空气源燃气热泵系统制冷特性

该文搭建了使用R410A制冷剂涡旋式压缩机的高能效空气源燃气热泵实验平台。在实验台上进行不同进水温度tw,in(8.8~18.8℃)、发动机转速Neng(1400~2400 r/min)、环境温度Tamb(24~43℃)、进水流量Gw(9.16~18.32 m^(3)/h)影响下的制冷特性研究,得到制冷量(Qc)、耗气功率(P_(gas))、压缩机功率(Pcomp)、一次能源利用率(RPER)、总一次能源利用率(RPER,all)及性能系数(RCOP)的变化规律。结果表明,RPER受RCOP与发动机热效率η_(eng)的双重影响,制冷运行时RPER、RPER,all与η_(eng)分别处于0.935~1.224、1.388~1.720与27.56%~35.25%之间。由不确定度分析可得Qc、P_(gas)和RPER的相对不确定度分别为5.61%、1.00%和5.70%,表明系统测试结果稳定可靠。