Demand Flexibility of Residential Buildings:Definitions,Flexible Loads,and Quantification Methods

This paper reviews recent research on the demand flexibility of residential buildings in regard to definitions,flexible loads,and quantification methods.A systematic distinction of the terminology is made,including the demand flexibility,operation flexibility,and energy flexibility of buildings.A comprehensive definition of building demand flexibility is proposed based on an analysis of the existing definitions.Moreover,the flexibility capabilities and operation characteristics of the main residential flexible loads are summarized and compared.Models and evaluation indicators to quantify the flexibility of these flexible loads are reviewed and summarized.Current research gaps and challenges are identified and analyzed as well.The results indicate that previous studies have focused on the flexibility of central air conditioning,electric water heaters,wet appliances,refrigerators,and lighting,where the proportion of studies focusing on each of these subjects is 36.7%,25.7%,14.7%,9.2%,and 8.3%,respectively.These flexible loads are different in running modes,usage frequencies,seasons,and capabilities for shedding,shifting,and modulation,while their response characteristics are not yet clear.Furthermore,recommendations are given for the application of white-,black-,and grey-box models for modeling flexible loads in different situations.Numerous static flexibility evaluation indicators that are based on the aspects of power,temporality,energy,efficiency,economics,and the environment have been proposed in previous publications,but a consensus and standardized evaluation framework is lacking.This review can help readers better understand building demand flexibility and learn about the characteristics of different residential flexible loads,while also providing suggestions for future research on the modeling techniques and evaluation metrics of residential building demand flexibility.

Seismic fragility of flexible pipeline connections in a base isolated medical building

Flexible pipelines are often used to connect hard pipes from a foundation to a superstructure to accommodate large deformation in the base isolation layer during an earthquake. Although Chinese seismic design guidelines suggest several confi gurations, they are diff erent from the designs that have been proven in practice, e.g., Japanese styles, and extensive experimental investigation into their seismic performance is required. Three types of seals, rubber-, metal- and asbestinebased, were tested quasi-statically with infi lled pressurized water at 2.5 MPa. The asbestine-based seal leaked at a smaller deformation than the other two types of seals. Based on the test results, three damage states were defi ned and the deformation capacity was estimated. To evaluate their performance, a three-dimensional model of a base-isolated medical building was developed using OpenSees, with the fl exible pipelines simulated by a mechanical model calibrated from the experimental data. A probabilistic seismic demand model and the fragility function of the fl exible pipelines were then developed to evaluate the seismic performance.

Exact solution of free vibration of adjacent buildings interconnected by visco-elastic dampers

With consideration of a high-rise coupled building system,a flexible beams-based analytical model is setup to characterize the dynamic behavior of the system.The general motion equation for the two beams interconnected by multiple viscous/visco-elastic dampers is rewritten into a non-dimensional form to identify the minimal set of parameters governing the dynamic characteristics.The corresponding exact solution suitable for arbitrary boundary conditions is presented.Furthermore,the methodology for computing the coefficients of the modal shape function is proposed.As an example,the explicit expression of the modal shape function is derived,provided only one damper is adopted to connect the adjacent buildings.Finally,to validate the proposed methodologies,three case studies are performed,in which the existence of the overdamping and the optimal damping coefficient are revealed.In the case of using one damper in connecting two similar buildings,the estimating equations for the first modal damping ratio are formulated.

Consumer Central Energy Flexibility in Office Buildings

Energy flexibility in buildings will play an important role in the smart energy system. Office buildings have more potentials to provide energy flexibility to the grid compared to other types of buildings, due to the existing building management, control systems and large energy consumption. Consumers in office buildings （building owners/managers and occupants） take a main role for adopting and engaging in building energy flexibility. This paper provides a systematic review of consumer central energy flexibility in office buildings with the discussion of social, technical and business aspects. This paper clarifies the correlations of consumers＇ concems, external influential factors, energy flexibility resources and technology with eight hypotheses. This paper suggests that technical solutions with the integration of distributed energy resources, building management and control system can boost energy flexibility in the office buildings.

Open Building as a Design Approach for Adaptability in Chinese Public Housing

Surveys on public housing in Northern China indicated that the common aim of Chinese public housing, which is to provide affordable housing, had been mostly satisfied. However, more than one fourth (29.9%) of the public housing units that were investigated were structurally modified by their occupiers for different layouts. This situation indicated that a fixed plan could not fulfill housing occupiers’ various requirements on spacing layout, and critical awareness had been shown that the adaptability of the public housing units was always ignored. Open Building is well organized and implemented in the field of residential area to increase adaptability and sustainability of dwellings. This paper reviewed the development of residential Open Building and attempted to reveal solutions for the design of adaptability in Chinese public housing. Based on the dwelling unit types, dwelling spaces, living modes and demographic conditions of the public housing units were investigated;and concerning the actual carried out adaptations in the public housing units, this research explored two levels of design and control methods: prototyping unit for possible layouts and flexible partitions for space-function reconfiguration. By adding design values of adaptability in public housing, key aspects showing?the potentials and challenges for the design of public housing were summarized for future reference.

Photovoltaics and Energy Storage Integrated Flexible Direct Current Distribution Systems of Buildings:Definition,Technology Review,and Application

For a future carbon-neutral society,it is a great challenge to coordinate between the demand and supply sides of a power grid with high penetration of renewable energy sources.In this paper,a general power distribution system of buildings,namely,PEDF(photovoltaics,energy storage,direct current,flexibility),is proposed to provide an effective solution from the demand side.A PEDF system integrates distributed photovoltaics,energy storages(including traditional and virtual energy storage),and a direct current distribution system into a building to provide flexible services for the external power grid.System topology and control strategies at the grid,building,and device levels are introduced and analyzed.We select representative work about key technologies of the PEDF system in recent years,analyze research focuses,and summarize their major challenges&future opportunities.Then,we introduce three real application cases of the PEDF system.On-site measurement results demonstrate its feasibility and advantages.With the rapid growth of renewable power production and electric vehicles,the PEDF system is a potential and promising approach for largescale integration of renewable energy in a carbon-neutral future.

Scalable and flexible porous hybrid film as a thermal insulating subambient radiative cooler for energy-saving buildings

Passive daytime radiative cooling(PDRC)is one of the promising alternatives to electrical cooling and has a significant impact on worldwide energy consumption and carbon neutrality.Toward real-world applications,however,the parasitic heat input and heat leakage pose crucial challenges to commercial and residential buildings cooling.The integrating of radiative cooling and thermal insulation properties represents an attractive direction in renewable energy-efficient building envelope materials.Herein,we present a hierarchically porous hybrid film as a scalable and flexible thermal insulating subambient radiative cooler via a simple and inexpensive inverse high internal phase emulsion strategy.The as-prepared porous hybrid film exhibits an intrinsic combination of high solar reflectance(0.95),strong longwave infrared thermal emittance(0.97),and low thermal conductivity(31 mW/(m K)),yielding a subambient cooling temperature of~8.4℃ during the night and~6.5℃ during the hot midday with an average cooling power of~94 W/m^(2) under a solar intensity of~900 W/m^(2).Promisingly,combining the superhydrophobicity,durability,superelasticity,robust mechanical strength,and industrial applicability,the film is favorable for large-scale,sustainable and energy-saving applications in a wide variety of climates and complicated surfaces,enabling a substantial reduction of energy costs,greenhouse gas emission and associated ozone-depleting from traditional cooling systems.

Identification of flexible buildings with bending deformation and the unmeasured earthquake ground motion

It is important to explore efficient algorithms for the identification of both structural parameters and unmeasured earthquake ground motion.Recently,the authors proposed an algorithm for the identification of shear-type buildings and unknown earthquake excitation.In this paper,it is extended to the investigation of the identification of flexible buildings with bending deformation and the unmeasured earthquake ground motion.In the absolute co-ordinate system,the unmeasured ground motion can be treated as an unknown translational force and a bending moment at the 1st floor level of a flexible building.Structural unknown parameters above the 1st story of the building can be identified by the extended Kalman estimator and the 1st story stiffness and the unmeasured ground motion are subsequently estimated based on the least-squares estimation.The proposed algorithm is further extended to the identification of tall bending-type buildings based on substructure approach.Inter-connection effect between sub-buildings is treated as‘additional unknown inputs’to sub-buildings,which are estimated by the extended Kalman estimator without the measurements of rotational responses.Numerical examples demonstrate the identification of a multi-story,tall bending-type building and its unmeasured earthquake ground motions using only partial measurements of structural absolute responses.

Simulating dispatchable grid services provided by flexible building loads:State of the art and needed building energy modeling improvements

End-use electrical loads in residential and commercial buildings are evolving into flexible and cost-effective resources to improve electric grid reliability,reduce costs,and support increased hosting of distributed renewable generation.This article reviews the simulation of utility services delivered by buildings for the purpose of electric grid operational modeling.We consider services delivered to(1)the high-voitage bulk power system through the coordinated action of many,distributed building loads working together,and(2)targeted support provided to the operation of low-voltage electric distribution grids.Although an exhaustive exploration is not possible,we emphasize the ancillary services and voltage management buildings can provide and summarize the gaps in our ability to simulate them with traditional building energy modeling(BEM)tools,suggesting pathways for future research and development.

基于BIM和语义网的轨道智能运维管理方法

建筑信息模型(BIM)技术对提高轨道运维管理效率具有重要的推进作用。然而,不同的检查和维护活动产生的数据异构性高、时空关系复杂,阻碍了BIM解释和整合数据的进程。为此,开发了一个基于工业基础类(IFC)和语义Web技术的轨道运维本体(TOMO),其具有3个功能:①基于轨道运维生命周期的应用需求,简化BIM模型信息;②引入映射规则,建立数据提取与转换模块,集成多源异构数据,结构化定义数据之间复杂的时空关系;③结合数据驱动技术,研究轨道精调智能优化的方法,提供弹性决策支持。最后,以某高速铁路静检数据为例,验证了该框架的有效性与实用性,对于促进领域数据互操作性、降低运维人员劳动强度和提高运维管理智能化程度具有实际的工程指导意义。

电网友好型建筑构建路径探索

建筑领域是电力系统重要终端用户,也是构建新型电力系统的重要环节。面向建筑零碳/低碳化构建目标和新型电力系统建设任务,建筑能源系统需要承担哪些新的任务?能够发挥什么样的作用?这些问题均亟待解答。为此,重点从新型电力系统对建筑能源系统提出的新的需求、需承担的新任务及建筑能源系统能够发挥的作用等方面进行探讨,建筑能源系统需要自身革新,在建筑全面电气化、提升建筑能源系统的柔性用电能力等方面寻求突破,在实现建筑自身“源储荷”各环节转变的基础上应当进一步挖掘灵活用电能力,成为新型电力系统中集“产消储调”于一体的友好用户。该研究将为深入认识建筑等用户侧在新型电力系统中需做出的变革、可发挥的作用提供有益探索和参考。

市电、光伏互补相变蓄能电供暖系统柔性负荷调节能力分析

随着我国可再生能源的跨越式发展,新能源电力消纳问题日益突出。文章构建了市电与光伏互补型相变蓄能电供暖系统,搭建了该系统动态热性能的数学模型,设计了系统的热电负荷柔性调节控制策略。针对北京市某低碳建筑进行情景分析,模拟研究了该系统的光伏消纳能力和柔性负荷转移能力。结果表明:在室内温度维持在18℃的情况下,采用屋顶光伏的系统能够降低案例建筑93.9%的峰电消耗量及23.9%的一次能源消耗量;与无光伏系统相比,使用不同安装形式及面积的系统,峰电消耗量能够降低75.1%~97.4%,且蓄电容量的提升对系统的柔性负荷转移能力提升有着显著作用,当蓄电池容量大于15 kW·h时,提升效果逐渐减小。

木结构斗拱出挑层数对建筑抗震性能的影响

木结构古建筑是世界建筑史的重要组成部分,目前的研究大部分集中在结构整体的抗震性能上,或者单独对构件的受力机理进行分析,主要的研究构件包括斗拱、柱、梁架等,但是在构件对整个结构抗震性能的影响方面研究较少。以殿堂型结构中的斗拱为研究目标,利用ANSYS和ABAQUS软件对其展开模态与动力时程分析。通过对不同层数的斗拱进行分析比对,总结出斗拱层数变化对其抗震性能的影响。结果显示,在地震波作用下两模型柱脚和柱顶位移相差不大,但屋脊位置的位移量五踩斗拱模型比三踩斗拱模型多40%,五踩斗拱的柱顶加速度比三踩斗拱的柱顶加速度小23.02%,五踩斗拱的屋脊加速度比三踩斗拱屋脊小24.27%,证明在一定范围内斗拱层数的增加有利于结构的耗能减震。

海中筑岛柔性组合围堰结构受力与变形特性

为了解决海上地连墙建设中,海上施工平台结构施工周期长、造价高等难题,利用锁扣钢管桩与工字形板桩组合围堰进行海中筑岛,围堰外侧设置平行钢丝索进行柔性约束,形成海中“锁扣钢管桩+工字形板桩+平行钢丝索”的柔性组合围堰结构。以传统刚性围箍和无围箍组合围堰结构作为对照,根据现场监测数据,对柔性组合围堰结构受力与变形特性进行分析。结果表明:与常规刚性围箍结构相比,在同样吹填土压力荷载作用下,柔性围箍结构中桩身最大弯矩减小约50%;无围箍结构中桩顶最大水平位移过大;在不均匀堆载作用下,刚性围箍自身应力会发生突变,而柔性围箍始终受拉,应力均匀分布。监测结果表明,柔性组合围堰结构实测应力、变形与计算一致性良好。

建筑区域广义储能资源的刻画与设计方法

面向碳中和目标,发展以风电、光电等可再生能源为主导的新型电力系统对于储能提出重大需求。建筑作为电力需求侧的主要部门之一,蕴含巨大储能潜力,不仅可实现自身柔性用能,还能主动参与外部电力系统调蓄。该文提出一种“等效电池模型”,定义等效充电功率、等效放电功率、等效储电量和等效综合效率,刻画建筑区域内3类最主要的虚拟储能资源(包括电动汽车+智能充电桩、暖通空调系统+建筑热容、可储能电器设备),并通过文献、实测和模拟数据给出典型工况下上述3类资源的关键参数取值范围。基于上述模型,提出建筑区域广义储能(包括传统储能和虚拟储能)的设计方法,实现减少柔性用能建筑的储能电池容量,并以典型办公建筑和住宅建筑为案例进行计算分析。提出的模型及方法可为城市能源系统的低碳设计规划提供有力支撑。

In search of optimal building behavior models for model predictive control in the context of flexibility

Model predictive control(MPC)is an advanced control technique.It has been deployed to harness the energy flexibility of a building.MPC requires a dynamic model of the building to achieve such an objective.However,developing a suitable predictive model is the main challenge in MPC implementation forflexibility activation.This studyfocuses on the application of key performance indicators(KPls)to evaluate the suitability of MPC models via feature selection.To this end,multiple models were developed for two houses.A feature selection method was developed to select an appropriate feature space to train the models.These predictive models were then quantified based on one-step ahead prediction error(OSPE),a standard KPI used in multiple studies,and a less-often KPl:multi-step ahead prediction error(MSPE).An MPC workflow was designed where different models can serve as the predictive model.Findings showed that MSPE better demonstrates the performance of predictive models used for flexibility activation.Results revealed that up to 57% of the flexibility potential and 48% of energy use reduction are not exploited if MSPE is not minimized while developing a predictive model.

基于室内设定温度调节的办公建筑空调用能柔性特性实验分析

空调系统作为建筑需求响应的核心,具有较大的柔性潜力。为了实现需求响应效益的最大化,针对性地实施优化配置与调控,必须明确空调用能柔性特性。然而,现有研究多依赖于模拟仿真探究需求响应期间的空调用能柔性特性,该方法往往无法准确反映实际运行条件,导致柔性特性不明晰,进而造成调控不合理、效率低等问题。针对以上问题,本研究选取2栋办公建筑进行了不同工况的需求响应实验,基于温变速率与预计平均热感觉指数(PMV)指标分析了设定温度调节期间的室内舒适度,并以柔性量、柔性比分析了不同工况下空调柔性可调潜力区间;同时,通过蓄热体内表面温度研究需求响应期间建筑蓄热体柔性特征。实测结果表明:在需求响应期间,当设定温度调节1~2℃时,均可维持较好的室内舒适度;同时,需求响应期间2栋建筑能够提供10~20 W/m^(2)的柔性负荷量,可实现28.3%~83.1%的负荷转移。本文结果可为空调系统柔性量化提供指标支撑与实测依据,对“双碳”目标下的建筑节能有参考价值。

建筑虚拟电厂参与需求响应市场的报量报价机制设计

高负荷密度的受端城市电网正面临日益严重的调节资源匮乏问题,城市建筑拥有大量中央空调、电动汽车等优质灵活资源,可通过聚合构建虚拟电厂参与城市电网的供需互动。随着需求响应市场的快速发展,灵活资源的市场化定价和交易成为趋势。为此,考虑到建筑和虚拟电厂两者的获益需求,设计了建筑虚拟电厂参与需求响应市场交易的报量报价机制。首先,根据建筑负荷的响应特性,将其分为无损可转移负荷、有损可转移负荷和有损可削减负荷,并分别提出其容量-成本的计算方法。然后,设计了同时保证建筑和虚拟电厂可靠收益的分配方法,以持续激励两者参与市场的积极性。在此基础上,建立了虚拟电厂参与市场交易的报价优化模型,实现不同场景下虚拟电厂的收益最大化。最后,通过算例仿真证明了所提机制在市场交易和收益分配方面的有效性。

基于点对点交易的智能楼宇电能优化调度

智能楼宇的产消者特性不仅可以促进RES(可再生能源)就地消纳,还能够通过P2P(点对点)电能交易机制协调内部柔性负荷降低用电成本。基于此,以智能楼宇中的WPV(风光)资源和柔性负荷为分析对象,提出了一种计及电能-调节容量联合交易的智能楼宇P2P优化调度策略。首先通过调整柔性负荷的用电来提供调节容量,消除WPV出力的预测偏差。然后提出电能-调节容量联合交易市场机制,将电能和调节容量同时作为市场的交易商品参与P2P交易。最后,采用算例对所提方法和模型进行分析,结果表明所提模型不仅可以有效增加WPV就地消纳量,还能促使市场用户积极参与P2P交易。

“光储直柔”建筑案例特征分析及系统设计相关问题探讨

“光储直柔”是解决建筑光伏发电与建筑终端用电时空错配难题等问题、促进光伏发电本地消纳的重要技术手段之一,也是以可再生能源为主体的新型电力系统实现“荷随源动”,提高供电安全性、可靠性与稳定性的重要支撑技术,对于零碳建筑和零碳电力的实现也具有重要作用。本文在对国内“光储直柔”建筑示范项目调研的基础上,汇集17个典型案例,分析了“光储直柔”建筑的气候区域、建筑类型、建筑规模等分布特征和建筑光伏、储能、直流配电、直流用电场景等技术特征,提出了建筑“光储直柔”的适宜应用场景、系统拓扑结构及电压等级选择建议和“光储直柔”系统的容量配置方法,指出了城市和农村建筑“光储直柔”发展的差异化技术路径,为建筑“光储直柔”的设计与推广应用提供一些有益参考。