Stochastic Flexibility Evaluation for Virtual Power Plants by Aggregating Distributed Energy Resources

To manage a large amount of flexible distributed energy resources(DERs)in the distribution networks,the virtual power plant(VPP)is introduced into the industry.The VPP can optimally dispatch these resources in a cluster manner and provide flexibility for the power system operation as a whole.Most existing studies formulate the equivalent power flexibility of the aggregating DERs as deterministic optimization models without considering their uncertainties.In this paper,we introduce the stochastic power flexibility range(PFR)and timecoupling flexibility(TCF)to describe the power flexibility of VPP.In this model,both operational constraints and the randomness of the DERs’output are incorporated,and a combined model and data-driven solution is proposed to obtain the stochastic PFR,TCF,and cost function of VPP.The aggregating model can be easily incorporated into the optimization model for the power system operator or market bidding,considering uncertainties.Finally,a numerical test is performed.The results show that the proposed model not only has higher computational efficiency than the scenario-based methods but also achieves more economic benefits.

Carbon emission impact on the operation of virtual power plant with combined heat and power system

A virtual power plant （VPP） can realize the aggregation of distributed generation in a certain region, and represent distributed generation to participate in the power market of the main grid. With the expansion of VPPs and ever-growing heat demand of consumers, managing the effect of fluctuations in the amount of available renewable resources on the operation of VPPs and maintaining an economical supply of electric power and heat energy to users have been important issues. This paper proposes the allocation of an electric boiler to realize wind power directly converted for supplying heat, which can not only overcome the limitation of beat output from a combined heat and power （CHP） unit, but also reduce carbon emissions from a VPP. After the electric boiler is considered in the VPP operation model of the combined heat and power system, a multi-objective model is built, which includes the costs of carbon emissions, total operation of the VPP and the electricity traded between the VPP and the main grid. The model is solved by the CPLEX package using the fuzzy membership function in Matlab, and a case study is presented. The power output of each unit in the case study is analyzed under four scenarios. The results show that after carbon emission is taken into account, the output of low carbon units is significantly increased, and the allocation of an electric boiler can facilitate the maximum absorption of renewable energy, which also reduces carbon emissions from the VPP.

Optimization Potentials for the Waste Heat Recovery of a Gas-Steam Combined Cycle Power Plant Based on Absorption Heat Pump

A new waste heat recovery system is presented to recover exhausted steam waste heat from the steam turbine by absorption heat pump(AHP) in a gas-steam combined cycle(GSCC) power plant. The system can decrease energy consumption and further improve the energy utilization. The performance evaluation criteria are calculated, and exergy analysis for key components are implemented in terms of the energy and exergy analysis theory. Besides, the change of these criteria is also revealed before and after modification. The net power output approximately increases by 21738 kW, and equivalent coal consumption decreases by 5.58 g/kWh. A 1.81% and 1.92% increase in the thermal and exergy efficiency is respectively obtained in the new integrated system as the heating load is 401095 kJ at 100% condition. Meanwhile, the appropriate extraction parameters for heating have been also analyzed in the two systems. The proposed scheme can not only save energy consumption but also reduce emission and gain great economic benefit, which is proven to be a huge potential for practical application.

Low-carbon Operation of Combined Heat and Power Integrated Plants Based on Solar-assisted Carbon Capture

Accelerating the development of renewable energy and reducing CO_(2)emissions have become a general consensus and concerted action of all countries in the world. The electric power industry, especially thermal power industry, is the main source for fossil energy consumption and CO_(2)emissions. Since solvent-based post-combustion carbon capture technology would bring massive extra energy consumption, the application of solar-assisted carbon capture technology has attracted extensive attention. Due to the important role of coal-fired combined heat and power plants for serving residential and industrial heating districts, in this paper, the low-carbon operation benefits of combined heat and power integrated plants based on solar-assisted carbon capture(CHPIP-SACC) are fully evaluated in heat and power integrated energy system with a high proportion of wind power. Based on the selected integration scheme, a linear operation model of CHPIP-SACC is developed considering energy flow characteristics and thermal coupling interaction of its internal modules. From the perspective of system-level operation optimization, the day-ahead economic dispatch problem based on a mix-integer linear programming model is presented to evaluate the low-carbon benefits of CHPIP-SACC during annual operation simulation. The numerical simulations on a modified IEEE 39-bus system demonstrate the effectiveness of CHPIP-SACC for reducing CO_(2)emissions as well as increasing the downward flexibility. The impact of different solar field areas and unit prices of coal on the low-carbon operation benefits of CHPIP-SACC is studied in the section of sensitivity analysis.

Performance Improvement of Combined Cycle Power Plant Based on the Optimization of the Bottom Cycle and Heat Recuperation

Many F class gas turbine combined cycle （GTCC） power plants are built in China at present because of less emission and high efficiency. It is of great interest to investigate the efficiency improvement of GTCC plant. A combined cycle with three-pressure reheat heat recovery steam generator （HRSG） is selected for study in this paper. In order to maximize the GTCC efficiency, the optimization of the HRSG operating parameters is performed. The operating parameters are determined by means of a thermodynamic analysis, i.e. the minimization of exergy losses. The influence of HRSG inlet gas temperature on the steam bottoming cycle efficiency is discussed. The result shows that increasing the HRSG inlet temperature has less improvement to steam cycle efficiency when it is over 590℃. Partial gas to gas recuperation in the topping cycle is studied. Joining HRSG optimization with the use of gas to gas heat recuperation, the combined plant efficiency can rise up to 59.05% at base load. In addition, the part load performance of the GTCC power plant gets much better. The efficiency is increased by 2.11% at 75% load and by 4.17% at 50% load.

电厂锅炉实验虚拟仿真系统建设与应用

为开展能动专业核心课程“锅炉原理”的实验教学,校企合作开发了电厂锅炉实验虚拟仿真系统。基于两相流动与辐射对流传热原理构建的仿真系统,由风烟和汽水两大模型构成,严格遵守质量、能量、动量守恒方程。变负荷虚拟实验显示,随锅炉负荷增加,热效率降低、燃料耗量增加。根据辐射传热原理,结合火焰平均温度计算发现:只有炉膛出口烟温增加,才能保证炉膛传热负荷增加,继而抬升排烟温度,导致排烟热损失变大、锅炉热效率降低。锅炉原理实验虚拟仿真,可训练学生运用锅炉本体热力计算原理分析问题的思维,是落实创新能力培养的重要举措。

CCPP机组余热锅炉高压蒸发器泄漏分析与处理

燃气-蒸汽联合循环机组(CCPP)作为高效能源转换系统,在钢铁等工业领域得到广泛应用。余热锅炉作为CCPP机组的核心部件,其稳定运行直接关系到整个机组的效率和安全性。文章针对某钢厂燃气轮机组配套余热锅炉高压蒸发器上部迎烟气面频繁泄漏问题进行了深入研究,分析泄漏原因为其下联箱内沉积物导致蒸发器管内水流量减小,进而产生汽水混合物的冲击腐蚀,同时炉膛局部区域的“烟气走廊”现象加剧了这一腐蚀过程。针对这一问题,采取更换泄漏管段、改造下联箱定排管系统以提高排污效率、修复和完善烟气挡板以减少“烟气走廊”形成、优化定期排污操作以及制定定期的检查和维护计划等措施,有效地解决了高压蒸发器的泄漏问题,提高了设备的稳定性和安全性。

基于风电分时电价的虚拟电厂参与清洁供暖运营优化方法

随着“碳达峰、碳中和”目标的提出,迅速发展的风电由于其随机性与波动性,面临突出的风电消纳问题。蓄热式电采暖作为中国北方地区主要供暖设备,虚拟电厂作为需求侧资源的主要聚合技术手段,聚合蓄热式电采暖的虚拟电厂可为消纳风电、提高风电利用率提供解决途径。对此,提出一种基于风电功率的分时电价划分方法,实现虚拟电厂聚合蓄热式电采暖参与基于分时电价的清洁供暖交易优化运营。首先,阐述虚拟电厂聚合蓄热式电采暖用户参与风电供暖的交易模式;其次,考虑热惯性对蓄热式电采暖和房屋进行精细化建模,提出基于层次凝聚聚类算法的分时电价方法,建立基于Weber-Fechner定律的负荷模糊响应模型,并构建多方主体综合收益最大、弃风量最小和负荷波动最小的虚拟电厂多目标运营优化模型;最后,通过算例分析风电消纳效果和虚拟电厂收益,验证该方法能够有效促进风电消纳、提高多方主体积极性,并具有一定的规模经济性,以期为缓解弃风问题提供参考。

考虑碳市场风险的热电联产虚拟电厂低碳调度

燃煤热电机组“以热定电”的运行模式会导致新能源消纳能力不足,且运行过程中会产生过高碳排放。为此,建立了考虑地源热泵、电转气(P2G)和碳捕集与封存(CCS)的热电联产虚拟电厂模型,并提出了基于碳市场风险的虚拟电厂低碳调度策略。利用自回归滑动平均模型及广义自回归条件异方差模型预测碳市场的次日碳价,并用条件风险价值模型衡量其波动风险;引入电制热设备地源热泵,协同P2G-CCS解耦热电联产“以热定电”运行约束;提出以各设备的运行成本、弃风弃光惩罚成本、碳交易及碳市场风险成本之和最小为目标函数的优化调度策略。算例结果表明:所提调度策略不仅能促进新能源消纳,提高经济效益,还可以降低系统碳排放。

计及蓄热罐与管网虚拟储能热电联供系统的经济运行优化分析

本文建立计及蓄热罐与管网虚拟储能热电联供系统模型,探讨不同储能装置配置(如无储能装置、含虚拟储能、含蓄热罐、含蓄热罐与虚拟储能)下负荷场景、燃煤价格、管网长度对系统运行成本的影响。结果表明:含蓄热罐与虚拟储能的储能配置使得热电联供系统的运行成本大幅降低,且当热电负荷波动较大时,运行成本降幅更大,如工业负荷场景下降幅达26.12%;燃料价格上涨使得系统运行成本线性增加,但相比于无储能装置,含储能装置系统的运行成本仍然较低,经济性更好;由于管网储能容量限制以及管网热损的影响,存在一个最佳管长使得系统运行成本最小。

多市场参与下热电联产虚拟电厂低碳经济协同调度方法

热电联产(combined heat and power,CHP)机组与虚拟电厂(virtual power plant,VPP)结合,可以有效提高能源利用效率,增强电力系统运行的可靠性及稳定性。为保证CHP-VPP灵活、低碳、经济运行,文中提出一种聚合风电、光伏、CHP机组、锅炉、碳捕集设备、燃气轮机、燃料电池、储能及电、热负荷的综合能源VPP,并在参与电-热-旋转备用-碳等多市场下,研究其低碳经济协同调度问题。首先,以各时刻VPP在多市场下整体净收益最大为目标,建立其CHP-VPP两阶段鲁棒优化调度模型;然后,考虑新能源出力、市场价格及负荷的不确定性,利用蒙特卡洛法进行场景削减,从而降低系统风险,增强其鲁棒性;最后,采用列与约束生成算法对模型进行求解,得到最恶劣场景下系统运行的经济性最优调度方案。仿真结果表明:所提综合能源VPP结构合理,可通过动态调整碳捕集设备及储能电池,达到平抑新能源出力波动的效果,从而实现碳排放的大幅降低;所提调度策略可有效保证源-荷-储多侧电、热资源的协同优化运行,提高VPP的灵活性、经济性和低碳性。

火电厂源侧综合能源系统集成及性能评估研究

本文建立了以火电厂为核心,消纳可再生能源并提供冷热电汽综合能源服务的一套能源系统,通过对整体系统及关键子系统热力性能分析,验证了提出模型和方法的有效性。并研究了一些关键运行参数对系统综合性能的影响,验证了提出模型和方法的有效性和优越性。结果表明:通过改变火电厂的源侧参数,可以提高综合能源系统荷侧的输出量;且生物质转化气对汽轮机发电功率的影响最大。热泵系统的负荷随着进入系统中的给水流量的增大而增大,利用汽轮机中的部分抽汽来驱动热泵系统,虽然发电功率下降了10.88%,但是却为用户提供了16.8MW的热负荷和16.2MW的冷负荷以及27.78t/h的蒸汽量。

多类型小容量火电机组热电解耦潜力与经济性对比评估

【目的】新能源发电存在输出功率和发电负荷的大幅波动和不稳定性问题,对电力系统稳定运行造成一定挑战。小容量火电机组热电解耦后参与电力系统整体运行,可提高电网调度效率与系统安全性,为此,采取多种热电解耦技术对3台小容量火电机组进行改造,并对各种技术路线进行了比较研究。【方法】通过使用EBSILON Professional软件进行模拟实验,对各种热电解耦方案在调峰负荷方面的潜力进行了评估和对比分析,并对改造后的经济性进行分析。【结果】水冷背压式机组热电解耦潜力空间较大,较其他机组有着明显优势,热泵改造机组最大供热下日利润提高217.18万元。随着抽汽热负荷变化,水冷凝汽式机组热电解耦潜力变化整体趋势平缓,最易控制,热泵改造机组最大供热下日利润提高202.25万元。空冷凝汽式机组热泵改造最大供热下日利润提高26.13万元。【结论】经过热电解耦升级的火电机组,能够大幅增强其调峰效果,热泵改造能有效提高日利润,从而提升整个发电系统的稳定性和发电效率。

考虑电-气-热耦合和需求响应的虚拟电厂优化调度策略

热电联产机组以热定电的工作方式无法同时满足冬季供暖效率最大化和电力调峰需求,存在发电出力调节能力不足的问题。针对上述问题,提出了考虑电、气、热能源耦合特性以及需求响应的虚拟电厂优化调度策略。首先,为提升热电联产机组向下调峰能力,引入电制气设备和碳捕集技术,构建新型的热电联产耦合模型。其次,为提升系统运行的灵活性,考虑峰谷分时电价、热价,建立综合需求响应机制。然后,为减少系统发电成本,引入电、热储能装置,以系统总成本和电、热储能运行成本最小化为目标建立虚拟电厂双层优化模型,并根据下层优化模型的KKT(Karush-Kuhn-Tucher,KKT)条件将双层模型转为单层并线性化处理进行求解。结果表明,所提方法的碳排放、运行成本以及新能源消纳率达到最优,提升了热电机组向下调峰能力,满足了系统低碳性、经济性的需求。

虚拟电厂供需侧双层协调自适应鲁棒优化调度

源荷预测是虚拟电厂(virtual power plant,VPP)制定未来调度计划的重要依据。提出一种基于多频组合短期源荷预测的VPP发电侧和用户侧协同优化调度方法。首先对时间序列的负荷数据进行集合经验模态分解(ensemble empirical mode decomposition,EEMD),并将其重构为高低2种频率,使用图卷积神经网络(graph convolution network,GCN)和长短期记忆网络(long short-term memory,LSTM)相结合的GCN-LSTM算法进行预测,并将多频模型得出的预测结果聚合形成不确定模糊集合。考虑需求响应,建立VPP双层优化调度模型。上层以用户利益最大化为目标,综合利用需求响应调度作用,基于制定的分时电价优化多类型可控负荷。下层以分布式电源出力成本最小为目标,同时兼顾供需两侧利益,实现VPP内部资源的优化,并运用改进列约生成算法将上述模型分解为主、子问题进行求解。通过算例分析对所构建的模型进行经济性、鲁棒性和有效性验证。

新型电力系统下虚拟电厂参与电-碳联合市场的竞标策略与价格传导机制

针对目前电力市场与碳市场未能协同增效的问题,该文梳理了电-碳市场的交互机理和价格传导效应。虚拟电厂运营商制定对外参与电-碳联合市场竞标、对内协调优化决策的双侧互动策略,构建包含风电、光伏发电、燃气轮机、储能、电动汽车及柔性负荷的多主体虚拟电厂模型参与电-碳联合市场,按照竞标策略根据电-碳价、竞标电量-碳排放量及储能、电动汽车的运行补偿机制进行动态博弈。算例表明电-碳联合市场下虚拟电厂内部分布式资源的积极性优于各主体独立参与市场,不同区域电网碳排放因子对虚拟电厂影响水平存在差异,碳-电价传导率的提升有利于当前电力市场效能和碳减排效果,为碳价机制设计提供理论引导。

固体电蓄热技术在虚拟电厂中的应用

分布式储能是虚拟电厂的重要组成部分。固体电蓄热作为一种储能技术,集电热转换和热能存储于一体,是虚拟电厂实现在时间和空间上对电能进行平移的有效手段。由于缺少分布式固体电蓄热设备协调运行的技术经验,限制了该技术的相关应用。为此,分析了储能在虚拟电厂中的重要作用和固体电蓄热设备的技术特点与运行特性,提出了固体电蓄热技术在虚拟电厂中的工作方式、控制模型和应用场景,为固体电蓄热技术相关研究提供一定参考。

基于船舶总能系统及余热利用的主机选型研究

以主推进发动机(又称“主机”)的定义及类型作为切入点,本文介绍了汽轮机、柴油机及燃气轮机等几类常规热力发动机,以及相关联合动力装置的技术特点。考虑到对民用船舶的经济性要求,开发充分利用余热的总能系统势在必行,从几类主机的技术特点出发,重点对其在总能系统中的应用可行性进行了分析。就目前而言,燃气轮机虽然单机热效率较低,但由于具有较高的排气温度及较大的流量,在船舶总能系统领域有着较好应用前景。燃气轮机与汽轮机联合组成的燃气-蒸汽联合动力装置(COGAS型联合动力装置)能显著提升系统热效率,达到与低速柴油机相近的水平。

某型直升机动力装置课程教学模式改革研究

针对原有航理基础教学模式单一、受训学员被动接受、培训效率低等现实问题,基于虚拟现实、增强现实和数字孪生等技术,构建具备发动机结构、工作系统的全息虚拟内容展示,以及发动机虚实内容混合交互、发动机特情动感体验的训练系统,实现驾驶座舱与发动机主要机件的模拟联动,以及发动机开车、关车程序的训练演示。课程教学改革解决院校航理教学阶段缺少实践教学支撑条件的问题,提高学员装备操作使用能力,促进知识向能力的转化。

涉及长输供热管网的热电联产改造研究

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