Transmission access raises unresolved economic issues

The electric utility industry is in the process of gradual change from a fully regulated industry to one of partial deregulation. Instead of relying on regulation to achieve a fair and equitable price to the consumer for electric energy, the reliance is placed more and more on market forces, through competition, to provide wholesale energy at the best market price. Clearly, open transmission access is required to create a viable competitive wholesale market for new generation resources. This article describes four unresolved, or at least partially unresolved, issues associated with transmission access for wholesale wheeling. Wheeling has been defined as the use of a utility's transmission facilities to transmit power for other buyers and sellers. At least three parties are involved in a wheeling transaction: a seller, a buyer, and one or more wheeling utilities that transmit the power from the seller to the buyer. This article considers wholesale or bulk wheeling only, and does not consider retail wheeling. The four unresolved economic issues described in this article pertain to transmission access: actual cost of providing transmission services; methodology or methodologies used in evaluating the cost of wheeling; contract path versus the actual power flows of the wheel; and issues associated with the formation of transmission regions     

Pinch analysis revisited: New rules for utility targeting

An extension of the utility targeting procedure in the pinch method for heat exchanger network synthesis is presented. The procedure is adequate for targeting the minimum utility use while guaranteeing that utilities will be utilized at conditions with the least departure from the pinch temperature. This approach tends to increase the thermodynamic efficiency of the network and to reduce the cost of utilities.     

New rules for the exergo-economic optimization methodology

New rules for the exergo-economic optimization methodology for multiproduct systems are presented. The rules include the loss of exergy unit cost due to irreversibilities when it is used in a subsystem. A comparison between the methodology using the new rules and with a different set of rules is presented here for the case of a cogeneration plant similar to the CGAM problem but using a combined cycle more detailed than CGAM. We found an exergy unit value lower than that found by Valero’s methodology for a waste stream.     

输电线路新型电磁防除冰

针对当前国内外高压输电线路除冰时需要线路停运,且需要较多的人力、物力、劳动强度大和危险等特点,提出了一种不停电电磁防除冰方法。基于高频电磁感应技术和热传导理论,建立了高压输电线路的防除冰物理模型,利用ANSYS参数化语言APDL进行编程,对输电线路物理模型中的电磁-热现象进行了耦合数值计算。通过对比不同电磁参数下输电线路温度的分布和变化情况,找到了影响输电线路温度变化的主要电磁参数,包括高频电流的频率、高频电流密度、感应线圈间距、感应线圈长度、感应线圈厚度和感应加热时间。据此对线圈尺寸进行了优化设计,使输电线路温度在0 ℃以上能够有效防除冰。     

Transmission in transition: bringing power to market

The US transmission network, representing only 7% of electric bills, is vital to a competitive electricity market. The author argues that the network needs to be controlled by people and firms that are completely disinterested in generation market outcomes. Transmission also needs to be controlled by its owners, who will regard further investments in the grid to be strategic, i.e., conducive to their business. Transmission is too important to be left to the government, or its ownership and control unnecessarily divided to the detriment of the public interest. He believes that the best structural form for transmission in the United States is a separate, for-profit independent transmission company     

输电线路冰灾事故原因及按新国标 提高设计标准的措施

为提高电网应对冰害的能力,科学指导未来输电线路的设计和建设,以2008年全国输电线路的冰害情况为背景,分析了覆冰倒塔的特点,指出覆冰过荷载、纵向张力差、绝缘子串覆冰闪络和导线舞动为覆冰倒塔的主要原因,并在新国标的基础上,提出防止冰灾事故的4项措施:缩小耐张段长度、抗冰加固措施、防舞动措施以及其他措施。     

Conductive heat extraction to a deep borehole: Thermal analyses and dimensioning rules

The ground is a virtually unlimited, ubiquitously accessible heat source and sink for heat pumps. Deep boreholes may be used as heat exchangers in the ground. We present an extensive analysis of such a heat extraction (or injection) borehole. The effects of stratification of the ground, climatic variations, geothermal gradient, and groundwater filtration are dealt with. A basic tool for the analysis is the solution for a heat-extraction step. The thermal disturbance at and near the ground surface is shown to be negligible. Thermal recharge in order to improve the heat-extraction capacity a few months later is shown to be futile. The thermal processes in the borehole are, in good approximation, represented by a single borehole resistance. Formulae that relate the heat-extraction rate to the required extraction temperatures are given. They are based on superpositions of steady-state, periodic, and extraction-step solutions. A response-test method is proposed for the determination of three important parameters: average thermal conductivity in the ground, borehole thermal resistance, and average undisturbed ground temperature.     

输电线路新型复合式基础试验研究

针对表层由薄粘土层覆盖的风化岩体输电线路地基,传统的原状土掏挖基础或岩石嵌固式基础均不能有效地发挥其功效,单独采用任何一种基础将不符合安全经济环保的要求,特将上述2种基础型式相结合,提出新型环保型复合式基础型式.选择典型场地进行原型试验,试验基础施工安全,坑壁稳定,根据试验结果,新型复合式基础充分发挥原状土和岩石地基的高承载、低变形的优势,并推导出新型复合式基础的抗拔承载力、抗倾覆承载力的计算公式,为新型复合式基础在输电线路杆塔基础中的应用提供技术资料.     

免开挖输电线路金属锚基础研究与应用

新型金属锚基础采用免开挖方式,充分利用原状土层力学性能来稳定杆塔。介绍了其研制过程及近年来在国内输电线路中应用实例,提出了设计应用于特高压输电线路工程杆塔基础的建议。     

新型电力系统背景下新能源送出合理消纳率研究

目的  大规模新能源渗透是未来新型电力系统的重要特征,新能源高比例消纳和电力系统的安全经济高效运行之间存在一定矛盾,从系统整体经济性角度出发,提出了一种新能源送出合理消纳率的计算方法。 方法  该方法以新能源接入的增量总成本最低为目标,综合考虑了电网消纳成本、新能源弃电成本和环保成本等,系统研究了合理消纳率关键影响因素。 结果  通过实际海上风电、陆上风电及光伏等算例验证了该方法的有效性,并通过多算例的集中探索,总结新能源送出合理消纳率及送出方案选择的一般性规律。 结论  所提方法为未来高比例新能源接入下的电网规划提供新思路,为指导后续新能源接入系统、调度运行等提供了重要参考。     

Shakedown of complex structures according to various hardening rules

This article is concerned with a review of the literature on shakedown problems of complex structures according to various hardening rules. Although many hardening rules have been developed, shakedown analyses for hardening materials in the literature are limited to the simple kinematic hardening rules of Prager and Armstrong–Frederick. In other words, much more advanced hardening rules may not be vital to decide whether a structure will shakedown or not. Results of shakedown analyses for some complex structures are included.     

Modern energy access to all in rural India: An integrated implementation strategy

Expanding energy access to the rural population of India presents a critical challenge for its government. The presence of 364 million people without access to electricity and 726 million who rely on biomass for cooking indicate both the failure of past policies and programs, and the need for a radical redesign of the current system. We propose an integrated implementation framework with recommendations for adopting business principles with innovative institutional, regulatory, financing and delivery mechanisms. The framework entails establishment of rural energy access authorities and energy access funds, both at the national and regional levels, to be empowered with enabling regulatory policies, capital resources and the support of multi-stakeholder partnership. These institutions are expected to design, lead, manage and monitor the rural energy interventions. At the other end, trained entrepreneurs would be expected to establish bioenergy-based micro-enterprises that will produce and distribute energy carriers to rural households at an affordable cost. The ESCOs will function as intermediaries between these enterprises and the international carbon market both in aggregating carbon credits and in trading them under CDM. If implemented, such a program could address the challenges of rural energy empowerment by creating access to modern energy carriers and climate change mitigation.     

新型法兰盘在输电塔中的研究

为了解决大型法兰连接问题,提出一种用于钢管塔上两圈螺栓的大型法兰构造型式,结合500kV崖门大跨越工程。用ANSYS程序对九个法兰节点进行了有限元分析,提出了用于大型法兰设计的计算公式。通过对计算结果的分析,得出大型刚性法兰能有效减小螺栓直径,具有良好的受力性能和较高的承载能力。     

T接输电线路故障测距的新型算法

针对T接输电线路故障测距三端数据采样的非同步,采用均匀传输线方程理论对T接输电线路的故障进行了分析与计算,提出了利用非同步数据采样方法判别故障分支,进而对故障的分支测距实现对T接输电线路的故障测距.该方法精度高、便于计算机实现.     

子宫肌瘤栓塞治疗的中长期临床观察

目的 评价子宫肌瘤栓塞治疗的中长期疗效.方法 对110例子宫肌瘤患者栓塞治疗,并追踪观察,追踪时间48～72个月,采用经阴道彩色超声复查,栓塞剂采用超液化碘油和平阳霉素混合液(51例)和聚乙烯醇微粒(直径350～700 μm,59例),观察其中长期临床疗效,并发症,性激素变化,怀孕妊娠分娩和肌瘤的再发情况等.结果 110例均进行了双侧子宫动脉栓塞,月经量过多症状改善有效93/94(98.93%),压迫症状改善26/26(100%).子宫体积减少51.5%±3.1%(t值2.861,P＜0.01).肌瘤体积     

Catalysis of ceria incorporated magnesium hydride: A follow up study

In continuation with the results explored in our recent previous study (https://doi.org/10.1016/j.apsusc.2021.150062), the current work sheds more light regarding the active in situ catalytic species in ceria additive loaded hydrogen storage system, MgH₂. For this study, two samples, MgH₂+0.167CeO₂ and MgH₂+0.5CeO₂ were processed through mechanical milling (5 h/200 rpm) and tests were conducted at various stages of hydrogenation/dehydrogenation cycles (cycles: 1, 5 and 10). Evidence for mild chemical interaction between MgH₂ and CeO₂ is observed at the time of mechanical milling, whereas strong redox type interaction is witnessed in the cycle tested samples. In-situ X ray diffraction study confirms that the thermally activated interaction between MgH₂ and CeO₂ does not produce MgO. In situ Raman spectra provide crucial evidence that reduced cerium oxides exist at all stages of interactions in the MgH₂/CeO₂ hydrogen storage system. Detailed advanced electron microscopic observations concur well with the in-situ X ray diffraction and Raman spectroscopy studies. Although Gibbs free energy calculations reveal the possible existence of cerium hydrides, owing to the structural similarities between CeH_x and CeO_x phases, the chemical identity of the most abundant catalytic product remains debatable. Regarding the catalytic mechanism, suppression of MgO rock salt formation is identified to be a key step where the role of CeH_x/CeO_x interfaces gains more importance.     

Energy access in Africa: Challenges ahead

This paper presents a review of the current situation and projections for energy access in Africa. The paper also presents several sets of ambitious energy access targets as agreed by the regional groupings within the region. The paper argues that achieving between 50% and 100% access to modern energy services by 2030 in Africa will require more effective mobilization and use of both domestic and external funding, and the development and implementation of innovative policy frameworks. The paper suggests that greater emphasis will need to be placed on productive uses of energy and energy for income generation in order to break the vicious circle of low incomes leading to poor access to modern energy services, which in turn puts severe limitations on the ability to generate higher incomes. The paper further suggests that if anything near the ambitious targets set by African organisations are to be achieved then it will be advisable to tap into the full menu of energy resource and technology options, and there will be the need for significant increases in the numbers of various actors involved together with more effective institutions in the energy sector.     

New methodology of solar radiation evaluation using free access databases in specific locations

In this paper, solar radiation obtained from different frequently used databases is compared in some different locations. In the analyzed databases, the data come from ground measurement networks, or from different models and with different resolutions. The proposed methodology assumes the hypothesis that the uncertainty of the databases is approximately the same as the meteorological uncertainty of the location. Therefore the heterogeneity of the observations is due to different observations. A weighted average is proposed taking into account different time and spatial characteristics of each database, and the estimation of standard deviation of weighted observations that derives the meteorological variability expected.