计及多能需求的综合能源服务商优化运行策略研究

随着分布式发电技术的不断成熟及发展,未来综合能源服务将是整合不同类型分布式发电并满足用户不同用能需求的有效途径.提出了一种含有多种分布式发电资源同时考虑多用能需求的综合能源服务商优化运行策略模型.首先建立了含有风电、光伏、燃气轮机、电储能、电热泵、辅助锅炉等分布式资源及电、热用能需求的园区综合能源系统优化调度模型;其次...     

Optimal distributed energy resources planning in a competitive electricity market: Multiobjective optimization and probabilistic design

This paper presents a probabilistic multiobjective framework for optimal distributed energy resources (DERs) planning in the distribution electricity networks. The proposed model is from the distribution company (DISCO) viewpoint. The projected formulation is based on nonlinear programming (NLP) computation. The proposed design attempts to achieve a trade-off between minimizing the monetary cost and minimizing the emission of pollutants in presence of the electrical load as well as electricity market prices uncertainties. The monetary cost objective function consists of distributed generation (DG) investment and operation cost, payment toward loss compensation as well as payment for purchased power from the network. A hybrid fuzzy C-mean/Monte-Carlo simulation (FCM/MCS) model is used for scenario based modeling of the electricity prices and a combined roulette-wheel/Monte-Carlo simulation (RW/MCS) model is used for generation of the load scenarios. The proposed planning model considers six different types of DERs including wind turbine, photovoltaic, fuel cell, micro turbine, gas turbine and diesel engine. In order to demonstrate the performance of the proposed methodology, it is applied to a primary distribution network and using a fuzzified decision making approach, the best compromised solution among the Pareto optimal solutions is found.     

State of the art of the virtual utility: the smart distributed generation network

The world of energy has lately experienced a revolution, and new rules are being defined. The climate change produced by the greenhouse gases, the inefficiency of the energy system or the lack of power supply infrastructure in most of the poor countries, the liberalization of the energy market and the development of new technologies in the field of distributed generation (DG) are the key factors of this revolution. It seems clear that the solution at the moment is the DG. The advantage of DG is the energy generation close to the demand point. It means that DG can lower costs, reduce emissions, or expand the energy options of the consumers. DG may add redundancy that increases grid security even while powering emergency lighting or other critical systems and reduces power losses in the electricity distribution. After the development of the different DG and high efficiency technologies, such as co‐generation and tri‐generation, the next step in the DG world is the interconnection of different small distributed generation facilities which act together in a DG network as a large power plant controlled by a centralized energy management system (EMS). The main aim of the EMS is to reach the targets of low emissions and high efficiency. The EMS gives priority to renewable energy sources instead of the use of fossil fuels. This new concept of energy infrastructure is referred to as virtual utility (VU). The VU can be defined as a new model of energy infrastructure which consists of integrating different kind of distributed generation utilities in an energy (electricity and heat) generation network controlled by a central energy management system (EMS). The electricity production in the network is subordinated to the heat necessity of every user. The thermal energy is consumed on site; the electricity is generated and distributed in the entire network. The network is composed of one centralized control with the EMS and different clusters of distributed generation utilities and heat storage tanks. Each of these clusters is controlled by a local management station (LMS). Every LMS has information about the requirements (heat, cold and electricity) of the users connected to its cluster and the state of the utilities and water level of the storage tanks in its cluster. The EMS receives the information from the LMSs and sets the electricity input or output of every cluster in the network. With the information ordered by the EMS, the LMS set the run or stand‐by of the utilities of its cluster. The benefits of the VU are the optimization of the utilization yield of the whole network, the high reliability of the electricity production, the complete control of the network for achieving the main aim of the EMS, the high velocity for assuming quick changes in the demand of the system and high integration of renewable energy sources, plus the advantages of the DG. This paper indicates the state of the art of the VU concept, analyses the projects that are being developed in this field and considers the future of the VU concept. Copyright © 2004 John Wiley & Sons, Ltd.     

分布式供能技术的发展现状与展望

在能源结构调整中，分布式供能技术引起了世界能源界的广泛关注，在国家大电站和电网能基本保证供电的情况下，分布式供能和中央电站供能的结合，对于保障国家供应和经济的发展将发挥重要作用。对分布式供能、分布式电力、分布式能源资源的概念进行了详细的说明，指出分布式供能技术就是以一些小型发电设备技术进步为依托，以靠近用户侧建立小型电站为主，并结合热电（冷）联产等应用拓展为前提的整体供能系统。对于该技术发展的经济和社会动力进行了分析说明，对分布式供能技术的特点、应用领域、涉及的主要技术内容和具体特性进行了介绍，最后对其发展前景进行了展望。     

Constructing an innovative Bio-Hydrogen Integrated Renewable Energy System

Hybrid Renewable Energy Systems (HRES) offer alternative energy options that deliver distributed power generation for isolated loads. However, the production of energy from both wind turbines and solar PV systems is weather-dependent. In this study, we developed an innovative Bio-Hydrogen Integrated Renewable Energy System (BHIRES) based on the integration of hydrogen generation from biomass fermentation, renewable energy power generation, hydrogen generation from water electrolysis, a hydrogen storage device, and a fuel cell providing combined heat and power. BHIRES can provide electric power, thermal energy, and hydrogen, with the additional function of processing biomass waste and wastewater. As indicated by results of the economic analysis conducted in this study, the cost of electricity and the average energy cost of using BHIRES are both lower than those for wind/PV/hydrogen HRES. Therefore, this system is ideal for users in remote areas such as islands, and farms in mountainous areas.     

The effectiveness of storage and relocation options in renewable energy systems

Across the world, energy planners and transmission system operators are faced with decisions on how to deal with challenges associated with high penetration levels of intermittent energy resources and combined heat and power (CHP). At the same time, distributed plant operators are eager to reduce uncertainties related to fuel and electricity price fluctuations. These interests meet-up for options in distributed supply that introduces the principle of storage and relocation, typically by integrating heat pumps (HP) or electric boilers (EBs) into the operational strategies of existing CHP plants. This paper introduces the principle of storage and relocation by energy system design, and proposes for the storage and relocation potential of a technology option to be found by comparing options by their storage and relocation coefficient R_c, defined as the statistical correlation between net electricity exchange between plant and grid, and the electricity demand minus intermittent renewable electricity production. Detailed operational analyses made for various CHP options within the West Danish energy system, point to the concepts of CHP-HP and CHP-HP cold storage for effectively increasing energy system flexibility. For CHP-HP cold storage, R_c increases from 0.518 to 0.547, while the plant's fuel efficiency increases from 92.0% to 97.2%. These findings are discussed within frameworks of renewable energy systems, suggesting principles for 1st, 2nd, and 3rd generation system designs.     

Evaluation of hydrogen storage technology in risk-constrained stochastic scheduling of multi-carrier energy systems considering power,gas and heating network constraints

The operation of energy systems considering a multi-carrier scheme takes several advantages of economical, environmental, and technical aspects by utilizing alternative options is supplying different kinds of loads such as heat, gas, and power. This study aims to evaluate the influence of power to hydrogen conversion capability and hydrogen storage technology in energy systems with gas, power, and heat carriers concerning risk analysis. Accordingly, conditional value at risk (CVaR)-based stochastic method is adopted for investigating the uncertainty associated with wind power production. Hydrogen storage system, which can convert power to hydrogen in off-peak hours and to feed generators to produce power at on-peak time intervals, is studied as an effective solution to mitigate the wind power curtailment because of high penetration of wind turbines in electricity networks. Besides, the effect constraints associated with gas and district heating network on the operation of the multi-carrier energy systems has been investigated. A gas-fired combined heat and power (CHP) plant and hydrogen storage are considered as the interconnections among power, gas and heat systems. The proposed framework is implemented on a system to verify the effectiveness of the model. The obtained results show the effectiveness of the model in terms of handling the risks associated with multi-carrier system parameters as well as dealing with the penetration of renewable resources.     

Infrastructure challenges for the built environment

The twin challenges of a lower-carbon future and national energy security are focusing attention on the most effective means of energy generation in the built environment. Efficiency gains are offered by the distribution of heat from community heating and combined heat and power (CHP) plant, which is presently underdeveloped in the UK by comparison with continental Europe. Natural gas is the preferred fuel for most of today's district energy systems which are technically developed, but proposed schemes must be tested against CHP ‘quality’ criteria to ensure there is not an increase in primary energy use compared to larger-scale central generation. Future district energy systems must aim to exploit local energy resources, such as biomass, wind and micro-hydro, and local thermal resources, such as solar collectors and ground source heat pumping. They may also incorporate novel forms of heat and power storage and load management.     

Large-scale integration of renewable and distributed generation of electricity in Spain: Current situation and future needs

Similar to other European countries, mechanisms for the promotion of electricity generation from renewable energy sources (RESs) and combined heat and power (CHP) production have caused a significant growth in distributed generation (DG) in Spain. Low DG/RES penetration levels do not have a major impact on electricity systems. However, several problems arise as DG shares increase. Smarter distribution grids are deemed necessary to facilitate DG/RES integration. This involves modifying the way distribution networks are currently planned and operated. Furthermore, DG and demand should also adopt a more active role. This paper reviews the current situation of DG/RES in Spain including penetration rates, support payments for DG/RES, level of market integration, economic regulation of Distribution System Operators (DSOs), smart metering implementation, grid operation and planning, and incentives for DSO innovation. This paper identifies several improvements that could be made to the treatment of DG/RES. Key aspects of an efficient DG/RES integration are identified and several regulatory changes specific to the Spanish situation are recommended.     

Life cycle assessment study of solar PV systems: An example of a 2.7 kWp distributed solar PV system in Singapore

In life cycle assessment (LCA) of solar PV systems, energy pay back time (EPBT) is the commonly used indicator to justify its primary energy use. However, EPBT is a function of competing energy sources with which electricity from solar PV is compared, and amount of electricity generated from the solar PV system which varies with local irradiation and ambient conditions. Therefore, it is more appropriate to use site-specific EPBT for major decision-making in power generation planning. LCA and life cycle cost analysis are performed for a distributed 2.7 kW_p grid-connected mono-crystalline solar PV system operating in Singapore. This paper presents various EPBT analyses of the solar PV system with reference to a fuel oil-fired steam turbine and their greenhouse gas (GHG) emissions and costs are also compared. The study reveals that GHG emission from electricity generation from the solar PV system is less than one-fourth that from an oil-fired steam turbine plant and one-half that from a gas-fired combined cycle plant. However, the cost of electricity is about five to seven times higher than that from the oil or gas fired power plant. The environmental uncertainties of the solar PV system are also critically reviewed and presented.     

Policymaking for microgrids

Technically, microgrids are emerging as an outgrowth of dispersed on-site and embedded generation via the application of emerging technologies, especially power electronic interfaces and modern controls, and similarly, microgrid economic and regulatory analysis is generally rooted in the same approaches used to evaluate distributed energy resources (DER). As in the economics of many traditional on-site generation projects, the economics of heat recovery and its application by combined heat and power (CHP) systems is central to the evaluation of microgrids, and integration of this capability is a key requirement whenever CHP appears as an option. The recovery of waste heat offers a key advantage to generation close to loads but at the same time adds significantly to analysis complexity because of the need to simultaneously meet requirements for electricity and heat, plus the inevitability of storage, both active and passive, entering the equation. More novel is the economics of power quality and reliability (PQR), which in microgrids can potentially be tailored to the requirements of end uses in a manner only considered to a limited degree in utility-scale system; e.g., by interruptible tariff options. The economics of microgrids arises from evaluation methods for on-site generation from the customer perspective and from the traditional utility economics of expansion planning from the utility perspective. Both of these areas have received considerable attention, so a growing toolkit exists, but methods need reinforcement in some key regards. Central to public policymaking will be consideration of the societal impact of microgrids, especially since their adoption may change macrogrid requirements.     

Paradigm shift in urban energy systems through distributed generation: Methods and models

The path towards energy sustainability is commonly referred to the incremental adoption of available technologies, practices and policies that may help to decrease the environmental impact of energy sector, while providing an adequate standard of energy services. The evaluation of trade-offs among technologies, practices and policies for the mitigation of environmental problems related to energy resources depletion requires a deep knowledge of the local and global effects of the proposed solutions. While attempting to calculate such effects for a large complex system like a city, an advanced multidisciplinary approach is needed to overcome difficulties in modeling correctly real phenomena while maintaining computational transparency, reliability, interoperability and efficiency across different levels of analysis. Further, a methodology that rationally integrates different computational models and techniques is necessary to enable collaborative research in the field of optimization of energy efficiency strategies and integration of renewable energy systems in urban areas. For these reasons, a selection of currently available models for distributed generation planning and design is presented and analyzed in the perspective of gathering their capabilities in an optimization framework to support a paradigm shift in urban energy systems. This framework embodies the main concepts of a local energy management system and adopts a multicriteria perspective to determine optimal solutions for providing energy services through distributed generation.     

Assessment of combined heat and power (CHP) integrated with wood-based ethanol production

A techno-economic assessment is made of wood-based production of ethanol, where the by-products are used for internal energy needs as well as for generation of electricity, district heat and pelletised fuel in different proportions for external use. Resulting ethanol production costs do not differ much between the options but a process where electricity generation is maximised by use of the solid residues as fuel for a combined cycle is found to give 20% more reduction of green-house gas emissions per liter of ethanol produced than the other options. Maximising electricity generation at the expense of district heat generation also allows more freedom when suitable sites for ethanol plants are looked for. Use of gasified biofuel for a combined cycle power plant is a demonstrated technology, however, the low ash and alkali content of the hydrolysis residue may allow direct combustion in the gas turbine topping cycle. This would reduce the necessary investment considerably. The potential advantages of using a combined cycle for maximising the electric power output from an energy combinate, producing ethanol and electricity from biomass, justifies further exploration of the possibilities for using hydrolysis residue directly as gas turbine fuel.     

Development of a sustainable multi-generation system with re-compression sCO2 Brayton cycle for hydrogen generation

Current research aims to develop, design, and analyze a novel solar-assisted multi-purpose energy generation system for hydrogen production, electricity generation, refrigeration, and hot water preparation. The suggested system comprises a solar dish for supplying the necessary heat demand, a re-compression carbon dioxide-based Brayton cycle, a PEM electrolyzer for hydrogen generation, an ejector refrigeration system working with ammonia, and a hot water preparation system. The first law and exergy analyses are implemented to determine the performance of the multi-generation plant with various outputs. Besides, the exergo-environmental evaluation of the plant is conducted for the environmental impacts of the plant. Furthermore, parametric analyses are executed for investigating the system outputs, exergy destruction rate, and system efficiencies. According to the results, the rate of hydrogen generated by means of the multi-generation power plant is determined to be 0.062 g/s which corresponds to an hourly production of 0.223 kg. Besides, with the utilization of the supercritical closed Brayton cycle, a power generation rate of 74.86 kW is achieved. Furthermore, the irreversibility of the overall plant is estimated as 535.7 kW in which the primary contributor of this amount is the solar system with a destruction rate of 365.5 kW.     

基于双层规划的电力生产与水资源管理耦合模型研究

火力发电作为耗能和耗水大户,对经济发展和环境保护具有重要影响,因此综合管理能源与水资源逐渐成为电力系统规划所关注的焦点。在兼顾经济因素和节水要求的前提下,采用双层规划方法对新疆巴州火电生产与水资源管理进行综合优化,其中上层模块以电力生产所需水量为目标,下层模块以电力生产管理经济成本为目标。通过对比双层和单层模型的优化结果,获得在节水降本前提下的电力生产、扩容方案、发电耗水及污染排放的最优方案。     

分布式冷热电联供能源系统与经济发展的关系

“十二五”期间中国15.7万亿元的增量经济大部分将在新规划的新区实现,但从各地正在规划和建设的新区情况来看,缺少从一次能源到终端需求的冷、热、电、汽全过程高效联供的分布式供能规划.据推算,若“十二五”期间新区能效不变,工业和建筑物燃料需求将增加3×108t标煤/a,而这显然是不可能的.新规划区域能源模式创新、提高能效是“十二五”中国经济发展的关键,采用天然气分布式冷热电联供能源系统(DES/CCHP),可使能源终端供应能效成倍提高.“十二五”期间中国必须从区域经济发展的能源保障高度来规划分布式冷热电联供,规划决策中要按照具体情况,以经济性、能效和碳排放指标是否最优为判据.CCHP可以调峰换取电价,实现互利双赢.制订区域DES/CCHP规划时应注意区域能源规划先行,摆脱热电联产的思维定势,树立冷热电联供的科学理念,不可忽视向居民供应生活热水起到的提高能效的作用,以及如何确定电力负荷、装机容量和节能减排指标等问题.     

Optimal operation of DC smart house system by controllable loads based on smart grid topology

From the perspective of global warming mitigation and depletion of energy resources, renewable energy such as wind generation (WG) and photovoltaic generation (PV) are getting attention in distribution systems. Additionally, all-electric apartment houses or residence such as DC smart houses are increasing. However, due to the fluctuating power from renewable energy sources and loads, supply-demand balancing of power system becomes problematic. Smart grid is a solution to this problem. This paper presents a methodology for optimal operation of a smart grid to minimize the interconnection point power flow fluctuation. To achieve the proposed optimal operation, we use distributed controllable loads such as battery and heat pump. By minimizing the interconnection point power flow fluctuation, it is possible to reduce the electric power consumption and the cost of electricity. This system consists of photovoltaic generator, heat pump, battery, solar collector, and load. To verify the effectiveness of the proposed system, results are used in simulation presented.     

Dynamic multi-objective optimization applied to a solar-geothermal multi-generation system for hydrogen production,desalination, and energy storage

The design of optimal energy systems is vital to achieving global environmental and economic targets. In the design of solar-geothermal multi-generation systems, most previous investigations have relied on the static multi-objective optimization approach (SMOA), which may leave considerable room for improvement under certain conditions. In this numerical study, the optimal condition at which to operate a solar-geothermal multi-generation system – which can simultaneously produce hydrogen, fresh water, electricity, and heat, along with storing energy ? is determined via a dynamic multi-objective optimization approach (DMOA). Optimization is performed using a combination of NSGA-II and TOPSIS, and the results are benchmarked against those of SMOA. The decision variables include the solar area, geothermal water extraction mass flow, and hydrogen storage pressure. The objective functions include the production of electricity, heat, hydrogen, and fresh water, along with the exergy and energy efficiencies and the payback period. It is found that when compared with SMOA, DMOA can significantly improve all the objective functions. The annual production of electricity, heat, hydrogen, and fresh water increases by 14.4, 16.1, 13.5, and 14.3%, respectively, while the average annual exergy and energy efficiencies increase by 5.2 and 3.0%, respectively. The use of DMOA also reduces the payback period from 5.56 to 4.43 years, with a 4.4% reduction in hydrogen storage pressure. This shows that compared with a static approach such as SMOA, DMOA can improve the exergy and energy efficiencies, economic viability, and safety of a solar-geothermal multi-generation system.     

Improvement of proton exchange membrane fuel cell overall efficiency by integrating heat-to-electricity conversion

Proton exchange membrane fuel cells (PEMFCs) have shown to be well suited for distributed power generation due to their excellent performance. However, a PEMFC produces a considerable amount of heat in the process of electrochemical reaction. It is desirable to use thermal energy for electricity generation in addition to heating applications. Based on the operating characteristics of a PEMFC, an advanced thermal energy conversion system using “ocean thermal energy conversion” (OTEC) technology is applied to exploit the thermal energy of the PEMFC for electricity generation. Through this combination of technology, this unique PEMFC power plant not only achieves the combined heat and power efficiency, but also adequately utilizes heat to generate more valuable electricity. Exergy analysis illustrates the improvement of overall efficiency and energy flow distribution in the power plant. Analytical results show that the overall efficiency of the PEMFC is increased by 0.4-2.3% due to the thermal energy conversion (TEC) system. It is also evident that the PEMFC should operate within the optimal load range by balancing the design parameters of the PEMFC and of the TEC system.