Research on Optimal Configuration of Energy Storage in Wind-Solar Microgrid Considering Real-Time Electricity Price

Capacity allocation and energy management strategies for energy storage are critical to the safety and economical operation of microgrids.In this paper,an improved energymanagement strategy based on real-time electricity price combined with state of charge is proposed to optimize the economic operation of wind and solar microgrids,and the optimal allocation of energy storage capacity is carried out by using this strategy.Firstly,the structure and model of microgrid are analyzed,and the outputmodel of wind power,photovoltaic and energy storage is established.Then,considering the interactive power cost between the microgrid and the main grid and the charge-discharge penalty cost of energy storage,an optimization objective function is established,and an improved energy management strategy is proposed on this basis.Finally,a physicalmodel is built inMATLAB/Simulink for simulation verification,and the energy management strategy is compared and analyzed on sunny and rainy days.The initial configuration cost function of energy storage is added to optimize the allocation of energy storage capacity.The simulation results show that the improved energy management strategy can make the battery charge-discharge response to real-time electricity price and state of charge better than the traditional strategy on sunny or rainy days,reduce the interactive power cost between the microgrid system and the power grid.After analyzing the change of energy storage power with cost,we obtain the best energy storage capacity and energy storage power.

ENERGY MANAGEMENT STRATEGY FOR PARALLEL HYBRID ELECTRIC VEHICLES

Energy management strategy (EMS) is the core of the real-time controlalgorithm of the hybrid electric vehicle (HEV). A novel EMS using the logic threshold approach withincorporation of a stand-by optimization algorithm is proposed. The aim of it is to minimize theengine fuel consumption and maintain the battery state of charge (SOC) in its operation range, whilesatisfying the vehicle performance and drivability requirements. The hybrid powertrain bench testis carried out to collect data of the engine, motor and battery pack, which are used in the EMS tocontrol the powertrain. Computer simulation model of the HEV is established in the MATLAB/Simulinkenvironment according to the bench test results. Simulation results are presented for behaviors ofthe engine, motor and battery. The proposed EMS is implemented for a real parallel hybrid carcontrol system and validated by vehicle field tests.

Estimate of China's energy carbon emissions peak and analysis on electric power carbon emissions

China＇s energy carbon emissions are projected to peak in 2030 with approximately 110% of its 2020 level under the following conditions： 1） China＇s gross primary energy consumption is 5 Gtce in 2020 and 6 Gtce in 2030; 2） coal＇s share of the energy consumption is 61% in 2020 and 55% in 2030; 3） non-fossil energy＇s share increases from 15% in 2020 to 20% in 2030; 4） through 2030, China＇s GDP grows at an average annual rate of 6%; 5） the annual energy consumption elasticity coefficient is 0.30 in average; and 6） the annual growth rate of energy consumption steadily reduces to within 1%. China＇s electricity generating capacity would be 1,990 GW, with 8,600 TW h of power generation output in 2020. Of that output 66% would be from coal, 5% from gas, and 29% from non-fossil energy. By 2030, electricity generating capacity would reach 3,170 GW with 11,900 TW h of power generation output. Of that output, 56% would be from coal, 6% from gas, and 37% from non-fossil energy. From 2020 to 2030, CO2 emissions from electric power would relatively fall by 0.2 Gt due to lower coal consumption, and rela- tively fall by nearly 0.3 Gt with the installation of more coal-fired cogeneration units. During 2020--2030, the portion of carbon emissions from electric power in China＇s energy consumption is projected to increase by 3.4 percentage points. Although the carbon emissions from electric power would keep increasing to 118% of the 2020 level in 2030, the electric power industry would continue to play a decisive role in achieving the goal of increase in non-fossil energy use. This study proposes countermeasures and recommendations to control carbon emissions peak, including energy system optimization, green-coal-fired electricity generation, and demand side management.

Improving energy utilization efficiency of electrical discharge milling in titanium alloys machining

Electrical discharge milling(ED-milling) can be a good choice for titanium alloys machining and it was proven that its machining efficiency can be improved to compete with mechanical cutting. In order to improve energy utilization efficiency of ED-milling process, unstable arc discharge and stable arc discharge combined with normal discharge were implemented for material removal by adjusting servo control strategy. The influence of electrode rotating speed and dielectric flushing pressure on machining performance was investigated by experiments. It was found that the rotating of electrode could move the position of discharge plasma channel, and high pressure flushing could wash melted debris out the discharge gap effectively. Both electrode rotating motion and high pressure flushing are contributed to the improvement of machining efficiency.

Congestion Management Strategies of Real-Time Market

The high penetration of distributed energy resources (DERs) will significantly challenge the power system operation and control due to their stochastic, intermittent, and fluctuation characteristics. This enhances the difficulty of congestion management of power systems in cross-border electricity market among different regions. For handling this, the Real-Time Market is proposed for balancing capacity trading against congestions. Several strategies for Real-Time Market dealing with congestions are proposed. The strategy of two-stage crossborder markets in Day-ahead, Intra-day and Real Time Market are introduced with the congestion constraints complied. Pre-Contingency strategy is proposed as the advance preparation for the future congestion, and In-Day redispatch is used for regulation. Accordingly, the requirements on facilities considering telemetry and remote control in a fast manner are discussed at last.

On Some Issues of Assessing the Efficiency of Renewable Energy Power Plants and the Share of Renewables in the World＇s Electricity Generation

The paper considers some issues related to the evaluation of power plants using renewable energy sources： energy efficiency, economic efficiency, the share of renewable energy in the world＇s electricity generation. At one time in the world there was a myth that more energy is expended on the construction of wind and photoelectric power stations, than they produce for the service life. Adherents of this myth are still found in Russia. In response to this myth, numerous studies have been carried out for the manufacturers of wind turbines and photovoltaic modules. It was proved that these power plants spent energy on them are produced within a period of less than a year and the energy consumed by them cannot be taken into account, since it is renewable. The author showed that power plants on organic fuel and existing nuclear plants using depleted fuel with a coefficient less than unity fundamentally cannot compensate for the energy used during their construction. In the world, the concept of the LEC （Levelized Energy Cost） produced by any power plant is widely used to estimate economic efficiency. However, the formula for determining it, in the author＇s opinion, contains an inaccuracy, which is proposed to be eliminated. At present, there are different opinions on the role of RES （Renewable Energy Sources） in the production of electricity. A summary indicator is the share of renewable energy in the world＇s electricity generation. The determination of the actual share of RES and the forecast of its growth is of significant importance for the development of the world economy. The author shows the differences in the estimates and suggests an approach for establishing agreed estimates.

Real-time optimization power-split strategy for hybrid electric vehicles

Energy management strategies based on optimal control theory can achieve minimum fuel consumption for hybrid electric vehicles, but the requirement for driving cycles known in prior leads to a real-time problem. A real-time optimization power-split strategy is proposed based on linear quadratic optimal control. The battery state of charge sustainability and fuel economy are ensured by designing a quadratic performance index combined with two rules. The engine power and motor power of this strategy are calculated in real-time based on current system state and command, and not related to future driving conditions. The simulation results in ADVISOR demonstrate that, under the conditions of various driving cycles, road slopes and vehicle parameters, the proposed strategy significantly improves fuel economy, which is very close to that of the optimal control based on Pontryagin's minimum principle, and greatly reduces computation complexity.

国有大型油气企业新能源发电项目经济评价探讨

国有大型油气企业基于减排降碳和可持续健康发展考量,积极探索新能源发电业务,投资项目经济评价方法和参数,成为影响新能源发电业务投资决策和高质量发展的决定性因素。基于经济评价基本原理,根据新能源发电项目技术经济特征,构建新能源发电项目经济评价方法和参数体系。折现现金流法仍然是新能源发电项目经济评价的主要方法,内部收益率和平准化度电成本是衡量项目盈利能力的重要指标。不同类型新能源发电项目经济评价方法具有较高的一致性,但应在投资构成、成本费用估算、收入与税金估算等方面体现差异,重点在营业收入估算中体现项目真正价值。在规制性配置储能要求以及储能收益政策有待落实的情况下,新能源发电项目效益有待提高,建议现阶段适当降低投资回报要求,尤其是出于市场拓展和协同发展目的的战略性新能源发电项目。项目电价和有效利用小时数对新能源发电项目的影响至关重要,应视情况合理选取参数。风光气电融合项目应分业务估算成本。国有大型油气企业应积极开展宏观配套政策和商业模式创新研究,以支撑新能源发电业务的高质量发展。

不同电激励方式对桥带电点火器的性能影响

为解决恒流发火在多点点火时的电源功耗和线缆能量损耗等问题,提出了采用电容放电激励方式起爆桥带电点火器,开展电容放电激励下桥带换能元的伏安特性、能量转换特性研究,并对比电容放电及恒流两种激励方式下桥带换能元的作用特性及桥带电点火器的输出特性。研究表明:采用电容放电激励起爆桥带换能元时,电容容值和充电电压的增加对桥带换能元的放电电压和电流峰值、断桥时间、能量利用率影响较大,达到桥带起爆的有效能量均为0.17J;采用电容放电激励方式时,桥带出现电爆炸现象,而采用恒流激励时桥带出现电热现象,两种不同电激励下双桥之间能量加载互不干扰;相比电容放电激励方式,采用恒流激励起爆电点火器时的建压时间、峰值压力及峰值时间均较大。

高比例新能源系统中各类电网侧储能设施调峰效益对比

储能电站的效益评估是储能大规模发展的关键。对高比例新能源系统电网侧储能的效益进行了全面评估,通过全时段8760 h生产仿真模拟,在保持系统供电可靠性不变的约束下,计算了抽水蓄能、压缩空气、电化学储能等储能电站的容量效益、电量效益,考虑了各类储能电站的运行策略。仿真模拟过程中,以周为节点,计算全年8760 h的系统运行状态,考虑了储能电站的运行效率、机组启停、跨日调节等因素,避免了典型日生产模拟无法模拟储能跨日调节导致的储能容量和电量效益评估失真的问题。最后,以中国西北地区实际高比例新能源系统为研究对象,分析了各种储能对减少火电装机、降低新能源弃电率的作用,研究结果可为中国高比例新能源系统电网侧储能电站的建设提供参考。

CNT/PVA@碳布膜的光电联合驱动界面蒸发性能研究

利用电能辅助的太阳能驱动界面蒸发技术是提高淡水产量的一个有效途径,但是如何绿色高效地获取淡水仍是一个挑战。利用带有孔洞的亚克力板作为支撑装置,在碳布上喷涂碳纳米管(CNT)和无水乙醇的混合溶液作为光热电热膜(CNT/PVA@碳布),与隔热装置和供水通道组成一个高效的界面蒸发系统。蒸发性能测试结果表明,该蒸发系统在1个标准太阳光照射下净蒸发速率达到1.5 kg·m^(-2)·h^(-1),而在与2 A电流的联合作用下,净蒸发速率高达5.08 kg·m^(-2)·h^(-1),比仅在1个标准太阳光照射下和仅提供2 A电流的蒸发速率之和高出0.6 kg·m^(-2)·h^(-1)。此外,这种蒸发系统构造简单易于规模化,为绿色高效地提高淡水产量提供了一个新的思路。

考虑多类型储能系统时空灵活性支撑的配电网日前优化调度策略

大规模分布式资源的接入使配电网的调控更加困难,如何合理有效地利用多元化资源以降低配电网的运行成本成为亟待解决的关键技术问题。考虑可移动式储能系统和电动汽车的互补特性,提出一种考虑多类型储能系统时空灵活性支撑的配电网日前优化调度策略,提高配电网系统的运行经济性。首先,建立电动汽车和可移动式储能系统的调度模型,并建立电动汽车停车生成率模型,简化了模型的复杂度,提高了求解效率;其次,引入基于集合的改进粒子群算法,并将其改造为适用于配电网优化调度的求解算法,提高其在离散空间寻优的求解效率;最后,在IEEE 33节点配电系统中对所提出的协同优化调度策略进行仿真分析,验证所提策略的有效性。

考虑送端资源与受端调峰模式匹配的多能互补清洁直流外送研究

为实现我国二氧化碳排放“2030年碳达峰、2060年碳中和”以及“构建以新能源为主体的新型电力系统”的目标,能源行业发展态势发生深刻转变,新能源渗透率需进一步提升。以金沙江流域为代表的西南清洁水电群是我国清洁电力外送的重要基地,利用大型梯级水电的调蓄能力,打捆近区风电、光伏电站外送,实现整体多能互补发电,可以为送端省份提供稳定、持续的清洁电力支撑。本文选取以西南水电多能互补基地为研究对象,按照区域内清洁能源弃电率最小为目标构建优化模型,提出一种基于模式匹配算法的兼顾送端资源匹配、受端负荷与调峰需求直流外送曲线优化方法。研究结果表明,利用大型水电的调节能力与外送通道,可以实现水风光多能互补,合理优化水电站风光配比,改善新能源外送的电力品质,提升新能源消纳水平以及外送通道的利用效率。

基于实际场景的电动汽车能量回收优化研究

为降低整车能耗并提升续驶里程,该文以某款纯电动汽车的能量回收系统为研究对象展开研究,通过对比传统电动车的真空助力制动系统和智能制动系统,优化了不同系统的制动能量回收扭矩策略,并分析了两种制动系统的能量回收率。在对中国工况进行分析的基础上引入实际驾驶场景路况,通过仿真分析和台架测试对整车能耗和能量回收率进行了对比。结果表明:中国工况和实际驾驶场景工况智能制动系统的能量回收率比真空助力制动系统分别高1.4%和1.1%,整车百公里电耗分别降低0.7%和0.6%,达到了降低整车能耗的目的。

基于集肤电伴热的集输管道节能评价研究

为实现集输管道热力消耗方面的节能挖潜,在热油管道温降理论计算基础上,根据集中加热和集肤电伴热两种原油加热输送方式的不同,探讨了不同因素对节能比的影响,研究了停输工况下集肤电伴热的加热效果趋势,掌握运行能耗、维温效果等多项技术参数。结果表明,理论上集肤电伴热恒优于集中加热方式;节能比与总传热系数、管径、管道长度呈线性负相关,与质量流量、原油比热容呈指数正相关,在一定条件下集肤电伴热的节能效果显著;现场管道中的电伴热停止工作后,38 h后温度才突破设定的下限温度,每年可节约热能15543.55 kW,相当于关停13台1160 kW的管式加热炉,可年减少碳排量10.215 t CO_(2)。

基于能量流的纯电动车节能降碳技术研究与应用

文章针对S项目续航不达标问题,设计了其能量流测试方案,通过构建基于能量流理论指导的整车能耗区域分析智能诊断系统,解决了能耗控制研究初期整车能量消耗分布情况难以界定的问题。基于CLTC工况,立足于整车能耗降低、成本管控强化、用户体验改善等多个优化目标,构建了用于汽车整车能耗控制的多目标协同仿真平台;建立了电动车能耗评价模型及理论回收算法,首次提出能量回收最佳回收率概念,基于整车风阻重量优化、传动效率提升,对回收策略及加速踏板map进行优化,获取整车最佳回收率;建立适用于企业纯电动及混动汽车降阻提效工具包;建立了一套具有企业特色的节能降耗技术研究与应用的流程体系。测试结果表明,该车续航提升40 km以上,电耗降低约0.5 kWh/100 km,并将此工具包应用于其他EV平台,预计节约成本约10亿/年。

等新能源消纳能力视角下的青海电网光热发电效益评估

大力发展新能源发电是我国电力行业发展的重要目标,但仅靠风电、光伏来完成新能源消纳占比要求,将导致弃电率高居不下。光热发电储热环节具有调节能力,利用光热发电代替风电和光伏,可降低风电和光伏弃电率,同时发挥容量效益,降低火电装机规模及煤耗。但光热发电的高成本限制了光热发电的发展,如何评估光热发电在电力系统中的效益,对光热发展具有重要意义。提出一种等新能源消纳能力约束下的光热电站效益评估方法,可综合考虑光热发电的新能源装机替代效益、降低火电装机的容量效益、减少火电发电量的煤耗效益,从而全面评估光热发电在系统中的效益。研究成果可为青海光热发电的效益评估提供参考。

凝汽器胶球清洗对凝汽器的效率提升策略研究

文章围绕凝汽器胶球清洗系统的设计优化和运行策略展开,通过选择适宜的胶球材质与尺寸,设计高效的循环清洗系统,以及精确控制清洗过程中的关键参数,旨在提升凝汽器的性能。

A new measurement method of crack propagation rate for brittle rock under THMC coupling condition

A new electrical method of conductive carbon-film(with waterproof and anticorrosion ability)was proposed to continuously measure crack propagation rate of brittle rock under THMC coupling condition.A self-designed coupling testing system was used to conduct THMC coupling fracture tests of the pre-cracked red sandstone specimens(where the temperature is only changed)by this new electrical method of conductive carbon-film.Calculation results obtained by the energy method coincide well with the test results.And the higher the temperature is,the earlier the crack is initiated and the larger the crack propagation rate and accelerated velocity are,which can prove the validity of the new electrical method.This new electrical method has advantages of continuously measuring crack propagation rate over the conventional electrical,optical and acoustic methods,and can provide important basis for safety assessment and cracking-arrest design of deep rock mass engineering.

Prediction of office building electricity demand using artificial neural network by splitting the time horizon for different occupancy rates

Due to the impact of occupants’activities in buildings,the relationship between electricity demand and ambient temperature will show different trends in the long-term and short-term,which show seasonal variation and hourly variation,respectively.This makes it difficult for conventional data fitting methods to accurately predict the long-term and short-term power demand of buildings at the same time.In order to solve this problem,this paper proposes two approaches for fitting and predicting the electricity demand of office buildings.The first proposed approach splits the electricity demand data into fixed time periods,containing working hours and non-working hours,to reduce the impact of occupants’activities.After finding the most sensitive weather variable to non-working hour electricity demand,the building baseload and occupant activities can be predicted separately.The second proposed approach uses the artificial neural network(ANN)and fuzzy logic techniques to fit the building baseload,peak load,and occupancy rate with multi-variables of weather variables.In this approach,the power demand data is split into a narrower time range as no-occupancy hours,full-occupancy hours,and fuzzy hours between them,in which the occupancy rate is varying depending on the time and weather variables.The proposed approaches are verified by the real data from the University of Glasgow as a case study.The simulation results show that,compared with the traditional ANN method,both proposed approaches have less root-mean-square-error(RMSE)in predicting electricity demand.In addition,the proposed working and non-working hour based regression approach reduces the average RMSE by 35%,while the ANN with fuzzy hours based approach reduces the average RMSE by 42%,comparing with the traditional power demand prediction method.In addition,the second proposed approach can provide more information for building energy management,including the predicted baseload,peak load,and occupancy rate,without requiring additional building parameters.