Study on Dynamics of Calorific Value, Biomass and Energy in Calamagrostis epigejos Population in Songnen Grassland

There were two peaks of seasonal changes of the calorific value in shoot and leaves of Calamagrostis epigejos in middle June and in the early August respectively. The calorific value in stem presented a single peak curve which appeared in the early August. The calorific values in inflorescence and dead standing showed a fluctuation and the peak value of inflorescence was in the early September and that of dead standing was in middle June. The seasonal changes of energy standing crop on the above-ground part synchronized with that of the biomass, which presented a single peak curve. The energy allocated to each organ in different seasons was in the order as leaves > stem > inflorescence in middle June, leaves > stem > dead standing > inflorescence in early July, leaves > stem > inflorescence > dead standing in middle July, and leaves > stem > dead standing > inflorescence from August to September. The vertical allocation of energy in the parts of above-ground was that the energy value gradually increased from the surface to the 20 cm high level and the maximum value at the 10 - 20 cin high level which made up 26.91% of energy on the above-ground partion, and then it was decreased. In the under-ground portion, the energy value progressively decreased with depth and the maximum value was at 0 - 10 cm depth layer which made up 69.01% of energy of the under-ground portion.

Exploring relationships of gross calorific value and valuable elements with conventional coal properties for North Korean coals

Coal in North Korean(NKC)is one of the most important products;however,based on various strategic policies its detail properties remain opaque even for general researchers.Since there are some signs for opening of the North Korea economy,this investigation as a modest effort is going to explore principle relationships among some essential parameters of NKCs such as gross calorific value(GCV),valuable elements and conventional properties by different statistical methods.Correlations indicated that ultimate parameters(carbon,nitrogen,and hydrogen)are the best GCV predictors for NKCs in comparison with proximate parameters(ash,moisture and volatile matter).Multivariable regression demonstrated that predicted GCV based on ultimate properties has a quite accuracy when correlation of determination was 0.99.Descriptive statistics processes showed that on average,the contents of valuable elements such as Ga and V for NKCs are higher than the world coal ranges and they can be considered as byproducts of combustion of NKCs.Pearson correlations indicated that Y may have a mixed organic-inorganic affinity while Ga and V mainly occur in the inorganic part(mineral matter)of NKCs.High inter-correlations between Ga-V and Al showed that aluminosilicates can be considered as their main bring minerals.

Prospects for key technologies of new-type urban integrated energy system

In recent years,primary energy consumption in China’s urban areas has increased rapidly,facing the problems of extensive use of energy,high energy consumption and insufficient intensified use of energy resources.Improving multienergy supply,increasing the proportion of clean energy and integrated energy efficiency are the main goals of urban development.The integrated energy system with multi-functional synergy and open trading will become one of the new directions for the development of new urban energy systems.This paper summarizes the main problems faced by the current towns and the characteristics of the new urban energy system,analyzes the development of new urban energy system from three aspects including energy interconnection hub infrastructure construction,energy management platform construction and energy value sharing,and forecasts the future development direction of new urban energy systems.

Prospects of key technologies of integrated energy systems for rural electrification in China

Owing to increasing environmental concerns and resource scarcity, integrated energy system shave become widely used in communities. Rural energy systems, as one of the important links of the energy network in China, suffer from low energy efficiency and weak infrastructure. Therefore, it is particularly important to increase the proportion of electricity consumption and build an integrated energy system for rural electrification in China(IESREIC) with a rural distribution network as the core, in line with national conditions. In this study, by analyzing the Chinese regional differences and natural resource endowments, the development characteristics of the IESREIC are summarized. Then, according to the existing rural energy problems, key technologies are proposed for the IESREIC, such as those for planning and operation, value sharing, infrastructure, and a management and control platform. Finally, IESREIC demonstration projects and business models are introduced for agricultural production, rural industrial systems, and rural life. The purpose is to propose research concepts for the IESREIC, provide suggestions for the development of rural energy, and provide a reference for the construction of rural energy systems in countries with characteristics similar to those of China.

Benefit allocation of electricity-gas-heat-hydrogen integrated energy system based on Shapley value

The integrated energy system is an important development direction for achieving energy transformation in the context of the low-carbon development era,and an integrated energy system that uses renewable energy can reduce carbon emissions and improve energy utilization efficiency.The electric power network and the natural gas network are important transmission carriers in the en-ergy field,so the coupling relationship between them has been of wide concern.This paper establishes an integrated energy system considering electricity,gas,heat and hydrogen loads;takes each subject in the integrated energy system as the research object;anal-yses the economic returns of each subject under different operation modes;applies the Shapley value method for benefit allocation;and quantifies the contribution value of the subject to the alliance through different influencing factors to revise the benefit allocation value.Compared with the independent mode,the overall benefits of the integrated energy system increase in the cooperative mode and the benefits of all subjects increase.Due to the different characteristics of different subjects in terms of environmental benefits,collaborative innovation and risk sharing,the benefit allocation is reduced for new-energy subjects and increased for power-to-gas sub-jects and combined heat and power generation units after revising the benefit allocation,to improve the matching degree between the contribution level and the benefit allocation under the premise of increased profit for each subject.The cooperative mode effectively enhances the economic benefits of the system as a whole and individually,and provides a useful reference for the allocation of benefits of integrated energy systems.The analysis shows that the revised benefit distribution under the cooperative model increases by 3.86%,4.08%and 3.13%for power-to-gas subjects,combined heat and power generation units,and new-energy units,respectively,compared with the independent function model.

考虑条件风险价值和阶梯碳交易的综合能源系统优化调度

为进一步提升综合能源系统环境效益,减少新能源出力不确定性所带来的潜在风险,提出了计及条件风险价值(conditional value at risk,CVaR)以及阶梯碳交易的综合能源系统优化调度模型。考虑到系统风电和光伏出力不确定性可能带来的影响,采用条件风险价值量度不确定性带来的潜在风险,并将碳捕获技术、电转气设备以及阶梯式碳交易机制引入系统调度模型,构建了综合考虑系统运行成本和碳交易成本的优化调度目标函数,由于所建立模型为混合整数规划问题,采用CPLEX求解器进行求解,设置4种场景进行验证分析,算例表明所提模型可有效减少二氧化碳排放,在兼顾经济性和环境性的同时引入CVaR,可避免由于忽略风光不确定性所带来的较为乐观的调度结果,使系统最终调度结果更为合理。

面向电-气综合能源系统的MEAV抗差状态估计法

为了实现电-气综合能源系统更为协调精确的状态估计,参考电网状态估计方法,基于最大指数绝对值(Maximum Exponential Absolute Value,MEAV)状态估计建立了电力-燃气网络的稳态模型。采用牛顿法作为基本算法,对系统进行能流计算以及MEAV等价模型的求解。最后,通过30个电网节点和22个燃气节点的耦合系统的仿真实验,验证了所提出的方法在获得电-气互联网络准确运行信息和抑制不良数据方面的能力。

冷水(热泵)机组能效测试方法及能效限定值的对比研究

冷水(热泵)机组作为集中空调系统的主要耗能设备,行业整体机组能效的提高会对按期实现“双碳”目标具有重大促进作用。GB/T 18430作为冷热水机组的基础性标准,修订工作已接近尾声,与之配套的能效标准GB19577—2015也需要进行相应的修订升级。对GB/T 18430中对舒适型冷水(热泵)机组的考核方法与对应美国和欧洲的进行了对比分析,构建了一个水冷式冷水(热泵)机组的理论模型,从而将中国、美国和欧洲能效标准中规定的限定值水平折算为同一个指标下进行对比。对比发现,我国目前水冷式机组的IPLV入门限定值分别提升5.4%和25.2%后可以达到美国能效标准A路径和B路径能效水平,提升13.4%后可与欧洲能效标准水平持平;风冷式机组能效限定值在数值上增加25.4%后可与欧洲能效标准基本持平。本文的工作为后续能效标准GB19577—2015的修订提供了参考依据。

癸硼烷改性JP-10燃料及其理化性质研究

近年来,新型高性能飞行器的发展对高热值燃料提出了更高要求,为进一步提高JP-10燃料的热值,采用癸硼烷进行改性,通过引入表面活性剂提高了癸硼烷在JP-10中的溶解度,获得不同癸硼烷含量的改性JP-10燃料。研究结果表明:含4%癸硼烷的JP-10燃料,在25℃下密度降低0.004 g·cm^(-3),黏度增加0.294 mPa·s,比热容提升了0.54 J·g^(-1)·℃-1;癸硼烷的添加使JP-10的热值显著提升,最大热值达到49.88 MJ·kg^(-1),与液氧完全燃烧的最大比冲同等条件下可提高2.92 s;同时,含4%癸硼烷的JP-10燃料,20℃下表面张力降低3.174 mN·m^(-1),还表现出了较好的雾化性能。本研究为新型高热值燃料的研制提供了重要的实验和理论依据。

考虑灵活性不足风险的园区综合能源系统优化调度

园区综合能源系统可以实现能源的高效利用,提高可再生能源的消纳能力。但是,随着可再生能源的渗透率升高,系统的运行灵活性需求激增,给其安全、经济运行带来了巨大挑战。在这种背景下,该文提出一种考虑运行灵活性不足风险的电-热园区综合能源系统优化调度方法。首先,综合考虑电力子系统与非电(热力)子系统的运行灵活性需求,给出园区综合能源系统的运行灵活性需求和供给的数学表达,并以运行灵活性裕量和运行灵活性不足风险成本作为系统运行灵活性的评价指标。然后,基于条件风险价值,推导出系统运行灵活性不足风险约束的数学表达。由于考虑灵活性不足风险的电-热园区综合能源系统优化调度问题具有随机性、非凸性、非线性和0/1离散整数变量,在数学上属于NP-hard问题,因此,在马尔可夫决策过程框架下对其进行建模,并采用近似动态规划算法对所提模型进行求解。最后,通过算例验证了所提方法的有效性。

考虑配电网灵活性不足风险的分布鲁棒低碳优化调度

双碳目标下高占比可再生能源接入配电网,其不确定性导致配电网灵活性需求剧增。为提高配电网灵活运行能力,减少碳排放,提出考虑配电网灵活性不足风险的分布鲁棒低碳优化调度方法。首先,考虑智能储能软开关作为网络灵活性资源,以减少线路阻塞并提高节点灵活性资源网络互济水平。引入功率传输分布因子表征灵活性供需在线路上的传输情况,提出资源灵活性裕度指标和线路容量裕度指标,评估配电网灵活性。其次,基于条件风险价值理论,推导出当资源-线路裕度不足时给配电网造成的灵活性不足风险。然后,考虑风光出力的不确定性与相关性,运用Frank-Copula函数生成风光出力场景,采用改进的KL散度构造概率分布模糊集。以综合运行成本最低为目标,建立分布鲁棒优化调度模型,采用列与约束生成算法求解。最后,通过算例验证表明,智能储能软开关的加入减少了线路阻塞的情况,所提方法能够减少配电网碳排放和灵活性不足风险。

考虑源荷相关性及条件风险价值的综合能源系统参与电能量-备用市场优化

为充分挖掘多种备用资源的调节潜力,针对综合能源系统同时参与电能量与备用市场时的优化调度问题进行了研究。考虑同一区域内能源和负荷的相关特性以及系统的运行风险,建立综合能源系统的日前调度随机优化模型。首先,采用基于Cholesky分解的拉丁超立方采样技术生成符合综合能源系统中源荷相关性的风-光-荷样本矩阵。其次,采用近邻传播(affinity propagation, AP)聚类算法生成典型场景。然后,以日前调度成本、备用资源调整期望成本及条件风险价值构成的调度总成本最低为目标,构建综合能源系统随机优化调度模型。最后,建立综合能源系统仿真模型,验证所提方法能够刻画综合系统内部的源荷相关性,并实现系统运行经济性和安全性的平衡。

煤炭热值对机组运行和电煤消费影响及其应对措施

煤质是影响电厂运行过程中节能环保水平以及电煤消费量的关键因素,从煤炭的发热量、灰分、水分、含硫含氮量等参数的变化分析了煤质对机组运行及电煤消费量的影响机理。结合江苏省主要燃煤发电企业近两年入炉煤热值、发电量及发电耗煤数据,定量分析了电煤热值变化对全省电煤消费量的影响,按照2022年全省煤电发电量测算,全省电煤年平均热值每提高418.4 kJ/kg,全年电煤消费总量减少约3.9×10^(6) t,减少CO_(2)排放约1.0×10^(7) t。因此,从强化源头管控、合理储配掺烧、实施更新改造、精细运行管理和优化存煤结构等方面,提出控制电煤热值的相关措施,降低机组发电煤耗,控制污染物排放,起到节能减排的作用。

抽水蓄能电站的多元化经济价值评价方法研究

抽水蓄能机组是目前电力系统中最成熟、功率与能量容量最大的储能技术手段。凭借其灵活、大容量和较低的单位容量建造与运行成本,在构建高比例新能源的新型电力系统中发挥着越来越重要的作用。另一方面,长期以来抽水蓄能电站的运行模式主要集中于削峰填谷和系统备用并获取收益,单一且较低的回报无法体现抽水蓄能电站的经济与技术价值。在市场环境下并结合抽水蓄能电站的多种运行模式,研究了抽水蓄能电站提供削峰填谷、调频、备用、容量市场价值以及黑启动的经济价值测算评估模型。以抽水蓄能电站经济收入最大化为目标,构建了抽水蓄能电站参与能量市场、调频市场与备用市场多品种经济价值分析模型。进一步结合黑启动与容量价值等多种补偿政策,形成了抽水蓄能电站的多元化经济评价方法。通过开展多种电价场景的算例分析,研究抽水蓄能电站在不同电价波动水平下的经济收益差异,证明了所提出的抽水蓄能电站多元化经济评价方法的可行性。

基于合作博弈的多园区互联综合能源系统低碳经济调度

在碳约束的背景下,多个园区级综合能源系统(park-level integrated energy system,PIES)间的能量共享有助于推动碳减排与经济发展。构建合理的碳交易机制,同时有效应对多园区系统在能源交互过程中所面临的利益冲突和可再生能源(renewable energy sources,RES)不确定性等问题是当下面临的关键挑战。为此,提出了不确定性环境下基于阶梯式碳交易机制的多园区综合能源系统低碳经济调度模型,以促进碳减排并实现多主体间的利益协调。基于态势感知技术,对系统运行面临的不确定性进行处理,以降低不确定性带来的风险;构建阶梯碳交易机制,以更好地管理多园区互联系统的碳排放总量;引入合作博弈理论表征多个园区系统间的能量交互过程,并采用Shapley值分配法来避免合作主体间的利益冲突。案例分析验证了所提模型在促进低碳目标实现、避免利益冲突以及提高系统运行灵活性方面的有效性。

Spacecraft Attitude Tracking and Energy Storage Using Flywheels

The control law of the flywheel in an integrated power and attitude control system （IPACS） for a spacecraft is investigated. The flywheels are used as attitude control actuators as well as energy storage device. A feedback control law for attitude tracking is firstly developed by using Lyapunov approach, and then a torque based control law of the flywheel is studied. The control torque vector of the flywheel is decomposed into three parts which are orthogonal to one another by using the method of singularity value decomposition （SVD）. One part is used to provide the attitude control torque, another part is used to store energy with given power, and the last part is used to accomplish wheel speed equalization to avoid wheel saturation caused by large difference among the wheel spin rates. A management scheme for energy storage power using kinetic energy feedback is proposed to keep energy balance, which can avoid wheel saturation caused by superfluous energy. Numerical simulation results demonstrate the effectiveness of the control scheme.

Multi-objective Optimal Dispatch for Integrated Energy Systems Based on a Device Value Tag

Due to the variety of devices and operating scenarios in an integrated energy system(IES),the optimal dispatch of an IES is usually complicated.An optimal dispatch method for an IES is proposed by defining the scheduling value for each device which can be different under various scenarios.First,thinking over the private and public attributes of each operating equipment,the evaluation system is established with the actual scenarios of economic,environmental and energy-savings being considered.Secondly,the economic,environmental and energy-saving benefits of each operating equipment are quantified by Technique for Order Preference by Similarity to an Ideal Solution(TOPSIS).Therefore,the scheduling value of the device is comprehensively assessed according to the specific scenario.Finally,decomposing the output of the device into direct available energy and indirect available energy,an optimal model is built with the maximum general production benefits as the objective,and is solved by MATLAB and CPLEX.The simulation results show that the evaluation system can reflect multiple values of devices.The proposed model can unify the modeling of optimal dispatch for different scenarios in the IES and can improve dispatch efficiency,while ensuring the accuracy of the results with high computation efficiency.

Bamboo Biomass for Bioenergy Production in Mauritius

Bamboo, globally renowned as being one of the fastest-growing plants in the world with versatile applications, has gained increasing attention during the past decades. It is being used by millions of people around the globe as a biomass resource for energy production, as timber for furniture making, in the food industry and many more. So far, on the Island of Mauritius, little to no consideration has been given to this fascinating plant. This paper presents the physical and chemical properties of two species of bamboo—Bambusia vulgaris and Bambusia bambos, compared to sugarcane bagasse for bio-energy production. Ten samples of each species were tested for gross calorific value (GCV), moisture, ash and chloride content. The results show that both species have a very good potential for energy recovery with a GCV of 16.77 MJ/kg for Bambusia vulgaris and 17.44 MJ/kg for Bambusia bambos, and are valuable sources of biomass with an average energetic yield of 717.8 GJ/ha/yr and 1587.1 GJ/ha/yr respectively. In comparison, the GCV for sugarcane bagasse was found to be 18.33 MJ/kg with an energetic yield of 824.9 GJ/ha/yr. Simultaneously, a research survey on community acceptance and perception of the Mauritian citizens towards the utilisation of bamboo biomass as an alternative to fossil fuels for bio-energy production was conducted via semi-structured questionnaires. The questionnaires were administered to a total of 54 respondents. 3 women and 3 men were randomly interviewed in each of the 9 districts of the island. The results show that the participants are very much aware of the many issues related to the exploitation of fossil fuels and support the use and implementation of renewable sources of energy for bio-energy production. Eighty percent of the participants supported the implementation of bamboo biomass in the overall energy generation mix in a bold move to lessen their ecological footprint.

计及条件风险价值和综合需求响应的产消者能量共享激励策略

随着分布式新能源的广泛普及和用户用能需求的多元化,在综合能源交易市场下研究如何优化产消者的能源调度,并解决其剩余能源的交易问题具有重要意义。为此,该文提出了一种由综合能源服务商主导的产消者能量共享优化激励策略。首先,构建由综合能源服务商主导的产消者能量共享实施架构,并给出产消者中的能量枢纽模型;其次,考虑到新能源出力和产消者用能的不确定性,建立了计及条件风险价值和综合需求响应的产消者模型以及综合能源服务商模型;然后,建立产消者能量共享模型,并提出了基于市场贡献的利益再分配策略;最后,通过仿真验证了所提策略能够有效降低产消者的经济成本,提高参与各方的积极性,并为产消者在经济效益和风险水平之间的平衡提供了参考。

基于C藤Copula及条件风险价值的综合能源系统灵活爬坡优化调度

随着可再生能源渗透率增加,净负荷波动幅度也随之变大。因此,该文针对净负荷不确定性变化,结合预测误差相关性与条件风险价值(conditional value at risk,CVaR),提出一种综合能源系统灵活爬坡优化调度方法。首先,通过神经网络模型预测风光荷初始功率,针对预测误差,运用C藤Copula函数构建多元随机变量预测误差的联合概率分布,并据此提出一种灵活爬坡产品设计方法;然后,在考虑净负荷不确定性带来的弃风光和切负荷条件风险价值的基础上,构建考虑灵活爬坡产品风险价值的综合能源系统优化调度模型。仿真结果表明,考虑净负荷预测误差相关性的优化使系统整体经济性提升1.22%,切负荷与弃风光总量减少了17.01%,验证该文方法的有效性。结合不同置信水平下的CVaR值,可为综合能源系统调度提供一定的风险参考。