自备电厂发展与节能减排目标的矛盾性

从全国及山西省自备电厂的特点和现行对自备电厂的政策分析,阐明自备电厂发展与节能减排目标的矛盾性,进而提出遏制自备电厂发展、促进节能减排工作的建议。     

龙岩市自备电厂存在的问题与对策

通过对龙岩市自备电厂情况的调研，分析了当前自备电厂建设管理中存在的问题．对规范企业自备电厂建设，加强运行管理等提出相关建议。     

自备电厂发展及相关问题探讨

本文通过对自备电厂的特点、现状及对自备电厂的现行政策的分析,阐述了自备电厂无序发展对资源、经济的影响,建议从法律手段和经济杠杆调节两方面来完善宏观经济政策,加大关停自备小火电机组的力度。     

对自备电厂管理的若干问题探讨

近年来电力紧缺,一些用电企业建了一批中小型机组的自备电厂,由于数量较多,缺乏有效管理,并网运行后影响到电力系统的安全经济。为此,本文对自备电厂作了分类及要求,以便于界定;并提出了关于自备电厂建设和加强对自备电厂管理的一些建议、要求和措施。     

自备电厂的并网对新疆电网运行安全的影响及其对策

通过对新疆电力企业的调查,对新疆电网中自备电网的运行进行了分析和思考.针对新疆自备电厂的特点、现状及对自备电厂的现行政策的分析,从国家能源政策贯彻实施、电力行业安全稳定运行、电力市场健康发展等多方面多角度,研究总结企业自备电厂对公用网厂健康发展所带来的影响,提出了相关的建议措施.     

变频调速器在自备电厂锅炉给水泵上的应用

一、概述目前，江苏省内不少企业设立了“自备电厂”，其综合用电率相对较高，自发电成本居高不下，怎样使发电成本降下来成了企业普遍关心的问题。由于自备电厂运行工况比较复杂，对锅炉的鼓、引风机实施变频调速改造较方便，但对锅炉给水系统的改造要求很高，应用变频调...     

自备电厂次中压发电锅炉水处理问题探讨

自备电厂次中压发电锅炉过热器经常发生爆管事故，其主要原因常与锅水水质不良，导致过热器内壁积附盐垢后产生局部蠕变变形，最终促使管壁爆破有关。本文结合上述原因的分析，对自备电厂次中压发电锅炉水处理问题提出了具体看法。     

利用后置机完善热力系统是企业自备电厂节能改造的好途径

对于有抽背式自备电厂的企业，利用后置机来完善热力系统，可取得显著的节能效果。     

某矿区自备电厂实施“节能减排、合理利用资源”增强市场竞争力的探索

某矿区自备电厂为适应电力商业化运营形势要求，探索立足矿区资源优势，对矿区洗煤厂生产过程中产生的废物一煤矸石进行综合利用发电，开展粉煤灰的综合利用。结合矿区发展，落实热负荷，实现热电冷三联产，发展循环经济，积极推广节能技术，实施“节能减排”，降低生产成本，以增强市场竞争能力。     

大庆油田自备电厂制粉系统干燥介质组成的探讨

本文是在总结了国内几座大容量褐煤电厂风扇磨制粉系统干燥剂组成配比的设计及运行实践的基础上,通过分析研究后提出大庆油田自备电厂风扇磨直吹式制粉系统的干燥剂,以采用热风、高温炉烟两介质组成为佳.可供电厂设计及运行参考.     

The influence of mass transport processes on the performance of the lead-acid cell on pulsed discharge

The effect of pulsed current discharge on lead-acid cell capacity has been examined in the light of the diffusive mass transport limitation of electrolyte to the reaction interface. It is shown that the capacity of a cell on pulsed discharge is expected to be identical with the capacity of the same cell subjected to constant current discharge. This prediction, which arises because the time scale of controller pulses is much shorter than that of diffusion relaxation, is largely supported by data reported in the literature.It has also been shown that cells subjected to pulsed discharge (pulse width δ, repetition time T) will experience heating effects which are increased by a factor of T/δ over cells discharged at the same mean constant current. In order to preserve cycle life it is recommended that cell cooling be optimized and some capacity be sacrificed to ensure that the cell is not overdischarged.     

Thin lead dioxide electrodes for high current density applications in semi-bipolar batteries

In the present paper, Planté-formed, thin-foil lead dioxide electrodes for applications in a semi-bipolar battery construction have been studied using impedance measurements, phase characterization and galvanostatic cycling. The effect of interparticle contact, IR-drop, porosity and mechanical pressure on the cell capacity were investigated in order to gain information about capacity-limiting parameters at high current discharges. The results showed that a more porous electrode received a capacity loss due to increased IR-drop, which in turn was caused by a decreased interparticle contact. The interparticle contact was found to be more important than porosity as a capacity-limiting factor. By exerting an external pressure over the cell, it was possible to increase the initial capacity for high current density discharges.     

Variability and phasing of tidal current energy around the United Kingdom

Tidal energy has the potential to play a key role in meeting renewable energy targets set out by the United Kingdom (UK) government and devolved administrations. Attention has been drawn to this resource as a number of locations with high tidal current velocity have recently been leased by the Crown Estate for commercial development. Although tides are periodic and predictable, there are times when the current velocity is too low for any power generation. However, it has been proposed that a portfolio of diverse sites located around the UK will deliver a firm aggregate output due to the relative phasing of the tidal signal around the coast. This paper analyses whether firm tidal power is feasible with ‘first generation’ tidal current generators suitable for relatively shallow water, high velocity sites. This is achieved through development of realistic scenarios of tidal current energy industry development. These scenarios incorporate constraints relating to assessment of the economically harvestable resource, tidal technology potential and the practical limits to energy extraction dictated by environmental response and spatial availability of resource. The final scenario is capable of generating 17 TWh/year with an effective installed capacity of 7.8 GW, at an average capacity factor of 29.9% from 7 major locations. However, it is concluded that there is insufficient diversity between sites suitable for first generation tidal current energy schemes for a portfolio approach to deliver firm power generation.     

Influence of equalization on LiFePO4 battery inconsistency

Capacity inconsistency among cells is a serious problem in battery energy storage systems. The inconsistency reduces battery pack lifetimes and increases their usage costs. Active balancing is an effective technique for performance equalization between cells. Here, a quantitative analysis method based on an active balancing circuit is developed to explain how battery capacity inconsistency is affected by balancing parameters. Four balancing parameters, namely, charge/discharge current rate, initial capacity difference before balancing, balancing current, and balancing time, have been considered to explain the effects on battery capacity consistency. The results indicate that (1) the inconsistency of batteries can be reduced more effectively for discharging with active balancing at small current rates; (2) for an improved balancing effect, it is necessary to maintain a high ratio (β) of balancing current to charging/discharging current during the balancing process; thus, a larger balancing current is significant; (3) the value of capacity difference reduction ratio (α) grows more dramatically in discharging at large initial battery capacity differences; and (4) when the balancing current only marginally changes, following the increase of current rate, the ratio (γ) of balancing time to charging duration decreases and the balancing effect becomes inconspicuous in charging, while γ increases and the balancing effect reduces in discharging. These influence regulations can help us make and optimize balancing control strategies for LiFePO₄ batteries. Copyright © 2017 John Wiley & Sons, Ltd.     

Preparation of N‐doped graphene powders by cyclic voltammetry and a potential application of them: Anode materials of Li‐ion batteries

Nowadays, doped graphenes are attracting much interest in the field of Li‐ion batteries since it shows higher specific capacity than widely used graphite. However, synthesis methods of doped graphenes have secondary processes that requires much energy. In this study, in situ synthesis of N‐doped graphene powders by using of cyclic voltammetric method from starting a graphite rod in nitric acid solution has been discussed for the first time in the literature. The N‐including functional groups such as nitro groups, pyrrolic N, and pyridinic N have been selectively prepared as changing scanned potential ranges in cyclic voltammetry. The electrochemical performance as anode material in Li‐ion batteries has also been covered within this study. N‐doped graphene powders have been characterized by electrochemical, spectroscopic, and microscopic methods. According to the X‐ray photoelectron spectroscopy and Raman results, N‐doped graphene powders have approximately 16 to 18 graphene rings in their main structure. The electrochemical analysis of graphene powders synthesized at different potential ranges showed that the highest capacity was obtained 438 mAh/g after 10 cycles by using current density of 50 mA/g at N‐GP4. Furthermore, the sample having higher defect size shows better specific capacity. However, the more stable structure due to oxygen content and less defect size improves the rate capabilities, and thus, the results obtained at high current density indicated that the remaining capacity of N‐GP1 was higher than the others.     

考虑开断顺序的断路器支路短路电流计算

针对目前断路器开断能力校核实践中只考虑短路点总电流而不考虑断路器实际可能通过的最大短路电流的问题,分析了同一支路中两侧断路器的动作工况对断路器通过的短路电流的影响,提出了计及断路器动作顺序的断路器支路可能出现的最大短路电流的计算方法。以某实际电网为例,定量计算、比较了流经断路器支路的最大短路电流和短路点总电流,指出目前以短路点总电流代替断路器可能流过的最大短路电流来校核断路器开断能力,因对断路器所需具备的断流能力要求过高而失当。     

基于石墨烯辐射强化散热的变压器过载能力提升技术研究

一般配电变压器的散热系统均未考虑过负荷情况,由于油温过高引发的安全事故时有发生,提出了一种提升变压器过载能力的运行可靠性方案,介绍了石墨烯辐射涂料的特点,基于石墨烯辐射涂料,开发设计了用于变压器强化散热的辅助散热模块,并对设计方案进行了验证,对于负荷波动较大的配电变压器,能有效降低油温,大幅提升现有变压器的辐射传热能力,进而提升变压器的过载能力,具备较好的实用价值。     

A high power quality anti-islanding method using effective power variation

Islanding phenomenon is undesirable because it leads to a safety hazard to utility service personnel and may cause damage to power generation and power supply facilities as a result of unsynchronized re-closure. In order to prevent the phenomenon, various anti-islanding methods have been studied. Until now, frequency or start phase shift methods of inverter current have much attention as active anti-islanding methods, which cause reactive power variation to the utility. However, these methods deteriorate usually the power quality like power factor or harmonic performance. This paper proposes a high power quality active anti-islanding method using effective power variation, which is implemented by periodically increasing/decreasing variation of inverter current magnitude. If it causes the large variation of inverter output voltage after islanding, active frequency drift (AFD) method as a simple anti-islanding method will be injected into the inverter current for a designed period and islanding can be detected. In case of large voltage variation when the grid is connected, AFD method will be removed after the designed period. Unlike most active anti-islanding method deteriorating power quality, the proposed method will have high performance of islanding detection and good power quality. For the verification of the proposed method, simulated results and experimental results in addition to analysis are presented using a 3 kW PV inverter.     

Numerical investigation of the leakage and explosion scenarios in China's first liquid hydrogen refueling station

Promoting fuel cells has been one of China's ambitious hydrogen policies in the past few years. Currently, several hydrogen fueling stations (HRSs) are under construction in China to fuel hydrogen-driven vehicles. In this regard, it is necessary to assess the risks of hydrogen leakage in HRSs. Aiming at conducting a comprehensive consequence assessment of liquid hydrogen (LH2) leakage on China's first liquid hydrogen refueling station (LHRS) in Pinghu, a pseudo-source model is established in the present study to simulate the LH2 leakage using a commercial CFD tool, FLACS. The effects of the layout of the LHRS, leakage parameters, and local meteorological conditions on the LH2 leakage consequence has been assessed from the perspectives of low-temperature hazards and explosion hazards. The obtained results reveal that considering the prevailing southeast wind in Pinghu city, the farthest low-temperature hazard distance and lower flammable limit (LFL) -distance occurs in the leakage scenario along the north direction. It is found that the trailer parking location in the current layout of the LHRS will worsen the explosion consequences of the LH2 leakage. Moreover, the explosion will completely destroy the control room and endanger people on the adjacent road when the leakage equivalent diameter is 25.4 mm. The performed analyses reveal that as the wind speed increases, the explosion hazard decreases.     

A critical review of using the Peukert equation for determining the remaining capacity of lead-acid and lithium-ion batteries

In many applications it is essential to predict the remaining capacity of a battery reliably, accurately and simply. Several existing techniques for predicting the remaining capacity of a lead-acid battery discharged with a variable current are based on variants of Peukert's empirical equation, which relates the available capacity to a constant discharge current. This paper presents a critical review of these techniques in the light of experimental tests that were carried out on two lead-acid commercial batteries. The relevance of these Peukert's equation based techniques to lithium-ion batteries is also discussed in the light of tests carried on a lithium-ion power battery. The basic conclusion of the paper is that Peukert's equation cannot be used to predict the state of charge of a battery accurately unless it is discharged at a constant current and constant temperature.