考虑电气转换及储能一体化的SOFC热电联供技术优化

当前热电联供技术优化方法,仅分析储能和发电装置的关系,导致优化后的热电联供技术,在环境温度和负荷率影响下,热电联供热力性能较低,为此提出考虑电气转换及储能一体化的SOFC热电联供技术优化。分析电堆电化学反应,确定SOFC产生的能源指标;依据SOFC电堆电化学反应计算结果,建立电气转换及储能一体化的SOFC热电联供系统模型结构,根据SOFC热电联供系统运行流程,分析SOFC发电装置、储能设备、热能处理设备之间的工作互通关系;基于分析结果,确定OFC热电联供技术优化目标,设计目标函数和最大装机容量约束并求解,实现SOFC热电联供技术优化。实验结果表明：在环境温度和负荷率影响下,考虑电气转换及储能一体化的SOFC热电联供技术优化方法,优化后的热电联供热力性能更高。     

基于热电联产运行模式的光热发电调峰策略

针对中国"三北"地区冬季供暖期因热电机组"以热定电"运行约束,导致系统调峰能力不足而造成的大量弃风问题提出一种基于热电联产运行模式的光热电站调峰策略。该文首先分析光热电站辅助供热后热电机组电热特性及其调峰能力变化情况,然后根据不同时段的负荷特性及热电机组运行状况制定出基于热电联产运行模式的光热电站在各时段的运行策略,在此基础上建立含光热电站、热电机组、纯凝机组、风电场的电力系统电热综合调峰优化模型。与传统模型相比,新模型增加了系统热平衡约束、热电机组的热电耦合约束、光热电站运行约束等。仿真结果表明基于热电联产运行模式的光热电站,通过辅助供热不但可有效提高电网的风电消纳水平,同时可避免运行成本较高的纯凝式机组频繁调节,提高系统运行的经济性。     

计及蓄电池使用寿命的热电联供型微电网经济优化

热电联供型微电网与当前能源互联网发展联系紧密,具有经济、节能、环保等优点。为了使热电联供系统的经济模型计算更加精确,文章在微电网经济调度优化模型中,考虑了蓄电池充放电深度和荷电状态SOC对蓄电池寿命的影响,利用加权吞吐量法计算其运行成本,建立了含风电机组、光伏电池、储能系统、燃料电池、空调机以及热电联供的并网型微电网系统的日运行成本优化模型,采用改进型遗传算法优化各微源出力,使其日运行成本最小。通过仿真算例,验证了考虑蓄电池使用寿命的微电网运行成本模型更符合实际运行工况。     

计及储能系统的微电网优化调度模型

为了缓解含风电、光伏等新能源微网并网对系统安全运行的影响,提出了在分时电价下,考虑储能系统的微网优化调度策略。以微网总成本最低为目标,分别考虑了投资成本、污染惩罚成本及主网购电成本,建立了微网主网联合运行优化模型,并以典型日负荷出力情况为例分析了不同情景下的优化结果。算例结果表明,所提策略和模型能有效实现微网优化调度,有效降低了含电动汽车和蓄电池等储能设备的微网年运行成本,同时能够保障微网和主网的联合安全运行。     

考虑需求侧响应的微网混合储能优化配置

在微网中配置混合储能并引入需求侧响应机制,有利于提高电网运行时的灵活性,降低分布式电源对电网带来的冲击。针对含风力发电机、光伏、储能的并网型微电网,引入需求侧响应机制,建立了以混合储能全寿命周期净现值、微网购电成本和需求侧响应成本为目标函数的微网混合储能优化配置模型,对混合储能容量进行优化配置,采用改进差分算法求解该模型。结合某地实际微网进行验证,结果表明,混合储能可有效改善分布式电源对微电网的影响,需求侧响应可显著降低混合储能成本,提高微网运行的经济效益,为类似微网混合储能优化配置提供了参考。     

基于氢气储能的热电联供微电网容量优化配置

以光伏系统、氢燃料电池、电解槽、储氢罐构建的热电联供微电网为研究对象,制定初始投资成本等年值以及年运行成本最小的优化目标,提出热电联供微电网热负荷满足率评价指标,针对系统运行的基本约束设计微电网控制综合策略,并以某地历史源荷数据为参考,建立满足工程应用的数学模型,采用粒子群优化算法进行求解,得到氢气储能的孤岛型微电网热电需求基本方案。从应用层面论证氢气储能替代电池储能的可行性,并进行微电网系统容量优化配置,可满足居民负荷供能需求,提高系统运行经济性,预期具有较好的应用前景。     

冷热电混合联供系统敏感性的多角度分析

为了评价冷热电三联供系统的运行性能,针对冷热电三联供系统及其对应的冷热电分供系统,建立了混合联供系统模型,研究了三联供系统的性能评价指标和优化策略。在最优一次能源节约率、最优运行成本节约率、以电定热及以热定电四种运行策略下,从负荷波动、燃料价格波动、网电价格波动和电制冷比改变的角度分析多联供系统的参数和指标变化。随着天然气价格的升高,联供系统全年的运行成本节约率不断下降;随着网电价格的升高,联供系统的运行成本节约率不断升高;选择合理的电制冷比可以提高系统运行指标。     

计及风光不确定性的新能源虚拟电厂多时间尺度优化调度

针对中国西北地区新能源消纳问题,该文聚合风力发电、光伏发电、光热电站、电储能装置组成虚拟电厂（VPP）,提出一种基于鲁棒随机优化理论的新能源虚拟电厂多时间尺度优化调度策略。首先对风力发电、光伏发电、光热电站与电储能装置进行数学描述,在此基础上建立VPP多时间尺度优化调度模型。在日前调度层中,以VPP运行效益最大为目标,依据风光日前预测出力建立日前优化调度模型;在时前调度层中,以VPP运行成本最小为目标,根据风光时前预测出力建立时前调度修正模型。同时,为了衡量风电、光伏发电出力不确定性对系统的运行影响,建立VPP随机优化调度模型。仿真结果验证该模型可提高运行效益与新能源消纳能力。     

基于NCPSO的微网群优化调度策略研究

传统的粒子群优化（PSO）算法因在微网优化中不易达到全局最优而导致微网运行成本过高,该文采用小生境混沌粒子群优化（NCPSO）算法对混合微网群的运行策略进行协同优化,以实现区域微网经济性最优、环境治理成本最低、风光等可再生能源利用率高等目的。根据所提出的调度策略,建立的优化调度模型包括动态电价下的负荷模型、经济收益模型以及成本模型等,使用NCPSO算法得到多微网在一个周期内的最佳运行状态,实现微网群系统综合能源的互动调控、空间互补。通过分析微网群的功率交互动态、可控能源的发电以及储能电池的荷电状态等,验证微网群的电力负荷响应动态电价,表明了NCPSO算法优化微网群运行的优越性、有效性。     

含氢储能的公路交通风、光自洽微网系统优化调度策略研究

该文构建以服务区微网净收益最大化为目标，以微网系统功率平衡为约束，包括蓄电池与氢能两种储能单元在内的风、光发电服务区微网优化调度模型。采用CPLEX求解器进行求解，并对纯蓄电池、纯氢储能、蓄电池与氢储能混合系统3种不同配置方案下的优化策略进行对比分析。研究结果表明：含氢储能的方案提升了风、光资源利用率的同时增强了系统供电可靠性，验证了该方案下优化调度策略的有效性。     

Combined heat and power systems with dual power generation units and thermal storage

The objective of this paper is to study the performance of a combined heat and power (CHP) system that uses two power generation units (PGU). In addition, the effect of thermal energy storage is evaluated for the proposed dual‐PGU CHP configuration (D‐CHP). Two scenarios are evaluated in this paper. In the first scenario, one PGU operates at base‐loading condition, while the second PGU operates following the electric load. In the second scenario, one PGU operates at base‐loading condition, while the second PGU operates following the thermal load. The D‐CHP system is modeled for the same building in four different locations to account for variation of the electric and thermal loads due to weather data. The D‐CHP system results are compared with the reference building by using conventional technology to determine the benefits of this proposed system in terms of operational cost and carbon dioxide emissions. The D‐CHP system results, with and without thermal storage, are also compared with that of single‐PGU CHP systems operating following the electric load (FEL), following the thermal load (FTL), and base‐loaded (BL). Results indicate that the D‐CHP system operating either FEL or FTL in general provides better results than a single‐PGU CHP system operating FEL, FTL, or BL. The addition of thermal storage enhances the potential benefits from D‐CHP system operation in terms of operational cost savings and emissions savings. Copyright © 2013 John Wiley & Sons, Ltd.     

Dynamic modeling and evaluation of solid oxide fuel cell - combined heat and power system operating strategies

Operating strategies of solid oxide fuel cell (SOFC) combined heat and power (CHP) systems are developed and evaluated from a utility, and end-user perspective using a fully integrated SOFC-CHP system dynamic model that resolves the physical states, thermal integration and overall efficiency of the system. The model can be modified for any SOFC-CHP system, but the present analysis is applied to a hotel in southern California based on measured electric and heating loads. Analysis indicates that combined heat and power systems can be operated to benefit both the end-users and the utility, providing more efficient electric generation as well as grid ancillary services, namely dispatchable urban power.Design and operating strategies considered in the paper include optimal sizing of the fuel cell, thermal energy storage to dispatch heat, and operating the fuel cell to provide flexible grid power. Analysis results indicate that with a 13.1% average increase in price-of-electricity (POE), the system can provide the grid with a 50% operating range of dispatchable urban power at an overall thermal efficiency of 80%. This grid-support operating mode increases the operational flexibility of the SOFC-CHP system, which may make the technology an important utility asset for accommodating the increased penetration of intermittent renewable power.     

Evaluation of a base‐loaded combined heating and power system with thermal storage for different small building applications

The objective of this paper is to demonstrate the advantages of using a combined heating and power (CHP) system operating at full load to satisfy a fraction of the facility electric load, that is, a base load. In addition, the effect of using thermal storage during the CHP system operation (CHP‐TS) is evaluated. A small office building and a restaurant with the same floor area, in Chicago, IL, and Hartford, CT, were used to evaluate the base‐loaded CHP and CHP‐TS operation based on operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDEs). Results indicate that, in general, the use of thermal storage is beneficial for the CHP system operation because it reduces cost, PEC, and CDEs compared with a CHP with no thermal storage. The CHP and CHP‐TS operation is more beneficial for a restaurant than for a small office building for the evaluated cities, which clearly indicates the effect of the thermal load on the CHP system performance. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimal operation of coproduction with storage

We discuss the optimal operation of a combined heat and power (CHP) plant with heat storage. The dynamics of the district heating (DH) network are also considered. The decision variables include production of heat and power, supply temperature and operation of heat storage. Heat demand for the DH system and shadow prices for the electrical power system are inputs to the production system. The optimization criterion is minimization of total costs over the planning period. A non-linear optimization model based on real data is formulated and representative case studies are performed.     

Evaluation of combined heat and power (CHP) systems performance with dual power generation units for different building configurations

This paper evaluates the economic, energetic, and environmental feasibility of using two power generation units (PGUs) to operate a combined heat and power (CHP) system. Several benchmark buildings developed by the Department of Energy simulated using the weather data for Chicago, IL, are used to analyze the proposed configuration. This location has been selected because it usually provides favorable CHP system conditions in terms of cost and emission reduction. For the proposed configuration, one PGU is operated at base load to satisfy part of the electricity building requirements, whereas the other is used to satisfy the remaining electricity requirement operating following the electric load. The dual‐PGU CHP configuration (D‐CHP) is modeled for four different scenarios to determine the optimum operating range for the selected benchmark buildings. The dual‐PGU scenario is compared with the reference building using conventional technology to determine the benefits of this proposed system in terms of operational cost, primary energy reduction, and carbon dioxide emissions. The D‐CHP system results are also compared with a CHP system operating following the electric load (FEL) and base‐loaded CHP system. For three of the selected buildings, the proposed D‐CHP system provides comparable or greater savings in operating cost, primary energy consumption, and carbon dioxide emissions than the optimized conditions for base loading and FEL. In addition, the effect of operating the D‐CHP system only during certain months of the year on the overall operational cost is also evaluated. Results indicate that not operating the D‐CHP system for the months where the thermal load is too low is beneficial for the overall system performance. Copyright © 2012 John Wiley & Sons, Ltd.     

考虑供热系统热储能特性的电-热综合系统随机优化调度模型研究

热电联产机组、热泵等装置的应用促进了电-热综合系统间的耦合关系,为风电的消纳提供了新途径。文章考虑了供热系统热储能动态特性,采用多场景法模拟风电出力不确定性,搭建了电-热综合能源系统随机优化调度模型。首先,针对供热管道传输时延动态特性,研究分析了其储热能力;其次,以电-热综合能源系统购能费用最低为目标函数,以热网约束、电网约束为约束条件,提出了综合系统能量最优化调度方案;最后,在IEEE33节点和6节点热网上进行算例分析,验证了模型的有效性。     

A comprehensive thermodynamic analysis of load‐flexible CHP plants using district heating network

Because of the rapid expansion of intermittent renewable energy, conventional coal‐fired power plants, including combined heat and power (CHP) plants, are required to improve the quick‐response ability to respond the changing demand of the grid. However, the flexibility of CHP plants is not easy to be improved because of the restriction of traditional load variation mechanism. This work presents a comprehensive thermodynamic analysis on the flexibility‐improving scheme using the thermal energy storage (TES) capacity of district heating (DH) network. A typical CHP plant and related DH network were selected as a case study. The flexibility demand under the context of renewables accommodation in the short timescale (counted by minutes) and the operational characteristics of CHP plants were analyzed on the basis of experimental data and thermodynamics. Besides, the influence of heat supply adjustment on heat users' indoor temperature was quantified with a dynamic model, and the thermal inertia of the DH network is discussed. Moreover, a thermodynamic model for the load variation processes simplified with operational characteristics was established to analyze the response ability improvement of CHP plants. Results of the case study show, the scheme can shorten approximately 34% of the response time while almost have no influence on the indoor temperature of heat users.     

Economic implications of thermal energy storage for concentrated solar thermal power

Solar energy is an attractive renewable energy source because the sun's energy is plentiful and carbon-free. However, solar energy is intermittent and not suitable for base load electricity generation without an energy backup system. Concentrated solar power (CSP) is unique among other renewable energy options because it can approach base load generation with molten salt thermal energy storage (TES). This paper describes the development of an engineering economic model that directly compares the performance, cost, and profit of a 110-MW parabolic trough CSP plant operating with a TES system, natural gas-fired backup system, and no backup system. Model results are presented for 0–12 h backup capacities with and without current U.S. subsidies. TES increased the annual capacity factor from around 30% with no backup to up to 55% with 12 h of storage when the solar field area was selected to provide the lowest levelized cost of energy (LCOE). Using TES instead of a natural gas-fired heat transfer fluid heater (NG) increased total plant capital costs but decreased annual operation and maintenance costs. These three effects led to an increase in the LCOE for PT plants with TES and NG backup compared with no backup. LCOE increased with increasing backup capacity for plants with TES and NG backup. For small backup capacities (1–4 h), plants with TES had slightly lower LCOE values than plants with NG backup. For larger backup capacities (5–12 h), plants with TES had slightly higher LCOE values than plants with NG backup. At these costs, current U.S. federal tax incentives were not sufficient to make PT profitable in a market with variable electricity pricing. Current U.S. incentives combined with a fixed electricity price of $200/MWh made PT plants with larger backup capacities more profitable than PT plants with no backup or with smaller backup capacities. In the absence of incentives, a carbon price of $100–$160/tonne CO_2eq would be required for these PT plants to compete with new coal-fired power plants in the U.S. If the long-term goal is to increase renewable base load electricity generation, additional incentives are needed to encourage new CSP plants to use thermal energy storage in the U.S.     

Risk-constrained scheduling of a CHP-based microgrid including hydrogen energy storage using robust optimization approach

Recently, the integration of various energy resources, including renewable generation and combined heat and power (CHP) units in microgrids, has created the opportunity of off-grid operation with a suitable range of reliability. This paper presents an optimization model to schedule an islanded MG with various resources, including CHP, photovoltaic (PV), and boiler, as the primary energy provision sources besides electric battery storage, thermal storage and hydrogen energy system (HES). The HES has the power-to-hydrogen (P2H) and hydrogen-to-power (H2P) modes, which increases the flexibility of the scheduling. The uncertainty management is the most essential task in the CHP-based MGs scheduling problem, since the power and heat productions are interrelated and can result in economic losses without enough deliberations. Hence, this paper proposes the robust optimization approach (ROA) to cope with the uncertainties associated with the PV production and electric and heat load demands. The robust counterparts are applied to the deterministic problem to create a tractable adjustable robust framework. The problem is structured as a mixed-integer linear programming (MILP) handled by the General Algebraic Modeling System (GAMS) using CPLEX solver. The results verified the effectiveness of the proposed robust counterparts in managing the associated risk. The results illustrated a conscious scheduling strategy under robust conditions. However, the more preserved decisions are taken, the higher operational cost is realized. In this regard, the increment of robustness level from the lowest value (deterministic condition) to the highest value (conservatism condition) increased the operation cost by about 43.29%.