Micro Hydro Power Plant for Sustainable Energy in Rural Electrification: A Case Study in Cameroon

The state of Cameroon, faced with the situation the electricity deficits, is promoting the development of renewable energies in general and to meet rural electrification needs in particular. The purpose of this work is to study the feasibility of the MHP of Batcheu, to show its contribution to sustainable development in this locality and to prove that it is a profitable project. After study, it appears that the waterfall of Batcheu is favourable to the establishment of a MHP with an installed power of 260 kW with an operating diagram corresponding to a Francis turbine. Given that it is a renewable energy that can supply more than 800 households in rural areas, its contribution to sustainable development is obvious. Its investment cost is estimated at 171,465,396 FCFA. It is a profitable project with a payback time of 7 years and 2 months.

Development of a Renewable Energy Based DC Excitation System in a Micro Hydro Power Plant

MHPPs （micro hydro power plants） have become prominent in hydropower plants as a solution to provide the energy demands of the grid. In this study, a new hybrid renewable energy based DC excitation system for synchronous generator in the developed MHPP system is introduced. Proposed hybrid DC excitation system consists of solar ＆ hydrogen energy based power generating systems. Hybrid renewable energy based system is used for the excitation of the synchronous generator in the MHPP test system. The renewables are used as a secondary energy source to provide the excitation current to a synchronous generator that generates energy in MHPP. A PV （photovoltaic） array is used as the main source of excitation, and a FC （fuel cell） stack is used for DC excitation in the lack of sunshine. In the experimental setup, an electrical control card is developed, and a microcontroller is used to perform the proposed excitation system. All experimental results obtained from 5 kW rated power MHHP test system. Experimental results show that, the proposed method provides the continuous excitation current, and the operation of the synchronous generator is uninterrupted. The proposed method is also practical and easily implemented for MHPP systems.

Technical and Economic Feasibility Studies of a Micro Hydropower Plant in Cameroon for a Sustainable Development

All serious projects over the world should respect the objectives of sustainable development. The contribution of every country against the climate change is request applied. The development of renewable energies is an effective contribution to solutions for this relevant question. Hydropower energy is one of most promising clean energy technologies. However, Micro Hydro Power Plants (MHPP) will be more promising than large hydro power stations. Cameroon has a great hydroelectric potential, but the access rate to electricity is still very low in rural areas of this country. The objective of this work is to do the technical and economic assessment of a MHPP in BAKASSA, which is a remote village in the West Region of Cameroon, in the intention to contribute to its sustainable development. The results of this study show that this MHPP project can be developed with installed power of 97 kW, where the Francis turbine is recommended. The investment cost evaluated at 88,440,068 FCFA. It is a profitable project with a maximum payback period of 9 years.

Sustainable Development around Small Scale Mining Areas by the Development of Micro Hydro Power: Application Cases in Cameroon

Of all the precious metals buried in the Cameroonian subsoil, gold is certainly the longest exploited. It has longtime been the subject of artisanal exploitation. In 2014, the monthly national production was estimated at around 170 kg. In these mining areas, people still live in a screaming precariousness of which one of the main causes is often the lack of electricity, because of the distance of these localities to the national electricity network. Cameroon has a great hydroelectric potential, but the access rate to electricity is still very low in isolate or rural areas of this country. The objective of this work is to show that it is possible to efficiently exploit gold in isolated areas and contribute to the sustainable development of these localities through the development of micro hydro power (MHP). The mining community of Tikondi in the East Region of Cameroon is the practical case study for an illustration. The results of this study show that the development of the MHP project can be developed with installed power of 87 kW, where the Banki-Michell turbine is recommended according to the Sulzer-Escher Wyss diagram. The investment cost evaluated at 79,832,775 FCFA (1 Euro = 656 FCFA). It is a profitable project with a maximum payback period of 8 years. This project can be easily funded by gold mining activity. That Tikondi’s MHP can make this village becoming attractive for others activities, improving the quality of education of children (there is not any school and lots of them do not go to school), the building of health centers and the quality of life in that locality and therefore contribute to their sustainable development too.

Crystal Plasticity Finite Element Process Modeling for Hydro-forming Micro-tubular Components

Micro-tubes manufactured by hydro-forming techniques have now been widely used in medical and microelectronics applica- tions. One of the difficulties in forming such parts is the control of localized necking in the initial stages of the deformation/forming process. A lack of microstructural information causes conventional macro-mechanics finite element（FE） tools to break down when used to investigate the localized microstructure evolution and necking encountered in micro-forming. An effort has been made to create an integrated crystal plasticity finite element（CPFE） system that enables micro-forming process simulations to be carried out easily, with the important features in forming micro-parts captured by the model. Based on Voronoi tessellation and probability theory, a virtual GRAIN（VGRAIN） system is created for generating grains and grain boundaries for micro-materials. Numerical procedures are devel- oped to link the physical parameters of a material to the control variables in a Gamma distribution. A script interface is developed so that the virtual microstructure can be input to the commercial FE code, ABAQUS, for mesh generation. A simplified plane strain CPFE modeling technique is developed and used to capture localized thinning and failure features for hydro-forming of micro-tubes. Grains within the tube workpiece, their distributions and orientations are generated automatically by using the VGRAIN system. A set of crystal viscoplasticity constitutive equations are implemented in ABAQUS/Explicit by using the user-defined material subroutine, VUMAT. Lo- calized thinning is analyzed for different microstructures and deformation conditions of the material using the CPFE modeling technique. The research results show that locations of thinning in forming micro-tubes can be random, which are related to microstructure and grain orientations of the material. The proposed CPFE technique can be used to predict the locations of thinning in forming micro-tubes.

Low-cost Remote Rain and Stream Data Acquisition System for Mapping of Potential Micro-Hydro Sites

The stream and rain data acquisition system presented in this paper makes the mapping of hydro potentials in the region or of the country economically and practically possible. Moreover, it can also serve as a flood warning system.

Technology Readiness of a Vertical-Axis Hydro-Kinetic Turbine

In this paper, the development of a vertical axis hydrokinetic twin turbine for harvesting energy from flowing water in man-made channels is described. The Technology Readiness Level (TRL) assessment procedure, developed by NASA and modified by the US Department of Energy, is followed and it is shown that the hydrokinetic turbine successfully reaches TRL 7, which is a full-scale, similar (prototypical) system demonstrated in a relevant environment. The concept of the twin turbine (TRL 1 - 3) is first validated and tested using a 1:10 scale laboratory model at Cardiff University and efficiencies of up to 75% are achieved (TRL 4 - 5). In order to justify system functionality and performance in a relevant environment as well as up-scalability, a 1:3 scale model of the twin turbine is implemented and tested in a discharge channel of a water treatment plant in Atlanta, thereby achieving TRL6. This paved the way for an application in the form of an array of ten full-scale twin turbine prototypes, including all relevant components such as housing, drive-train, gear-box and generator. Successful deployment and testing in the South Boulder Canal near Denver means that the hydrokinetic twin turbine system reached TRL7.

水储微电网并/离网运行稳定性分析

小水电配以储能组成水储微电网系统,可以显著提高小水电运行效率与当地配电网的供电可靠性。仿真分析了水储微电网并/离网运行功率、频率稳定性问题,首先给出小水电运行机理及模型、储能及其控制模型;其次利用MATLAB/Simulink仿真软件搭建水储微电网模型;最后通过仿真水储微电网并/离网的电气变化,分析小水电和储能的运行稳定情况。结果表明,并网下储能可以在短时间内平衡负荷的扰动,维持断面的平衡;离网下储能能快速调节输出功率,维持微电网系统的稳定。

基于管状结构的液–固接触摩擦纳米发电机

构建微能量收集系统并将其作为传感器分布式电源或自驱动传感器具有重要意义。基于摩擦起电原理,设计并制作一种管状结构的单电极液-固接触摩擦纳米发电机(liquid-solid triboelectric nanogenerator,LS-TENG),实现对固–液摩擦过程所产生电荷的直接提取,无需传统摩擦纳米发电机的静电感应过程。首先,基于多物理场耦合分析液-固接触摩擦纳米发电机工作原理,解析电荷转移过程中的电势分布。其次,试验探究液体流量、管道长度、内径和材料对摩擦纳米发电机输出特性的影响情况。最后展示所构建的摩擦纳米发电机作为微电源的负载供能特性。研究发现,LS-TENG的输出电压、电流、转移电荷与流量成正比,与管道内径成反比;LS-TENG输出电能经过整流桥可实现对电容充电储能,在610 mL·min-1的流量下可驱动至少40个LED灯珠。相关研究成果为构建基于管状结构的微水能收集系统提供参考。

摆动式超声单波束水下微地形探测实验台建立

为了验证摆动式超声单波束探测方法能否适用于深海富钴结壳微地形探测,在实验室里建立探测实验台。从水声换能器的等角度摆动精度分析,采用了圆柱凸轮机构作为探测装置的机械传动机构;从探测精度和分辨率两方面考虑,确定了水声换能器的工作频率为500 kHz,波束角为3°;通过一系列已知参数研制出收发一体式水声换能器探测的水下测量仪,并编写出数据采集与处理软件;分别对材质为普通河沙、模拟海泥和硬质水泥做成的水平地形进行11次探测实验。结果表明,实验台的垂直探测精度达到了厘米级。由此证明了摆动式超声单波束探测能够达到钴结壳微地形探测的精度要求。

微型低比转速混流式水轮机的水力特性分析

本文介绍了一种由冷却塔中冷却循环水驱动的微型水轮机。该机流量限于循环水流量、功率限于风机功率、水头依赖流量与功率;其蜗壳平面尺寸小,不设导水机构,转轮流道狭长。为了解该水轮机的水力特性,采用数值模拟与试验相结合的方法对其进行研究。研究表明:对于同一水轮机,其内流场特性表现出相似性,能量和压力脉动等水力特性也表现出相似性,水力效率相等,水力损失相等。该水轮机的水力效率较低,水力损失较大,其水能主要损失于引水部件,其次是转轮;由于引水部件距离转轮近,其固定导叶叶道的水力振动幅度达到10%以上。

三峡水库干流消落带泥沙沉积影响因素

为揭示三峡水库消落带不同自然环境因素对泥沙沉积过程的影响及判别人类活动的干扰程度,采用原位观测方法,对三峡水库干流消落带的泥沙沉积量及其潜在影响因素(消落带微地形、河流水文泥沙条件、消落带土壤侵蚀、消落带植被状况和人类活动)展开调查、分析和量化测算,并利用典型相关分析和方差分析,研究不同因素对泥沙沉积量的影响。结果表明:1)库尾江津—涪陵河段以人类活动的影响最为剧烈,自然环境因素与泥沙沉积量均无显著关系。2)库中涪陵—奉节河段以消落带地形特征中的坡度和高程影响较为明显,二者与泥沙沉积量的相关程度分别为-0.508和-0.714;坡度越小,泥沙沉积越多;高程越低,消落带被含沙水流淹没的时间越长,泥沙沉积量也越多。3)库首奉节-秭归段则以坡度的影响为主,其与泥沙沉积量的相关程度为-0.517,坡度越小,泥沙沉积越多,不同高程间的泥沙沉积量并无太大差异。研究说明,三峡水库干流消落带泥沙沉积影响因素主要包括消落带坡度、高程、河流水沙条件和人类活动4种,植被盖度对消落带泥沙沉积过程没有影响,4种因素的影响范围存在较明显的空间变异性。

PI-PD控制在风水微网中的应用

风水微网中,风电的间歇性和波动性容易造成微网功率波动频繁,恶化微网电能质量。为平滑风水微网输出功率,提出将PI-PD控制方法应用到微网内水电机组控制中,采用频域分析法分析了常规PID控制及PI-PD控制对水电机组的控制效果,提出改善水机动态响应过程的参数调整方法;建立了风水微网仿真模型,通过时域仿真比较了微网内水机采用常规PID、模糊PID和PI-PD算法的控制效果,并分析了PI-PD控制参数对微网内部动态响应的影响。理论和仿真分析结果表明,与常规PID及模糊PID相比,微网中水机采用PI-PD控制能够获得较快的调节速度、较小的反调量;合理整定PI-PD控制参数值,能够缩短微网动态响应时间,抑制微网功率振荡,保证微网安全稳定运行。

风水储微电网优化调度策略研究

为了缓解风电因随机波动性对电网造成的冲击,增强风电的可控性,提出一种基于分频段补偿法的风水储微电网优化调度策略。该策略根据水电机组输出带宽,通过小波分解法对风电功率信号进行多尺度分解,得到水电机组和储能系统初级功率指令,再根据水机爬坡能力,对初级功率指令进行修正得到最终功率指令。基于MATLAB/Simulink平台建立了风水储微电网仿真模型,分析了所提调度策略与现有策略的控制效果,结果表明,所提调度策略能减小储能所需容量,降低储能配置成本;改善了微网内水机过渡过程,有利于微网稳定运行;提高了风电的可控性,使微网有功输出更平滑。

微灌用水力旋流分离器内流体流动基本方程的建立

用数学解析的方法描述水力旋流器的流场特性,一直是水力旋流器流场研究的重要方面,也是许多理论与实际工作者孜孜以求的目标。将针对水力旋流分离器的结构特征,在前人研究成果的基础上,建立柱坐标系下、球坐标系下、直角坐标系下旋流分离器内流场流动基本方程。

原油脱盐脱水技术综述

介绍了国内外在原油乳状液稳定性方面的理论研究现状,以及国内外多种原油脱盐脱水技术,包括施加电场、超声波辐射、微波辐射、液-液旋流分离、膜分离、冷冻解冻等各项技术的原理、特点、研究进展及应用状况。指出动态旋流分离技术和微波法破乳在未来具有较好的工业应用前景,而新型破乳剂的开发和电脱盐设备的不断改进是目前原油脱盐脱水技术发展的主导方向。

基于需求侧响应的水风互补微电网容量优化配置

针对微电网内源荷两端匹配性较差的问题,本文以含径流式小水电的水风互补微电网为研究对象,提出了一种考虑需求响应的优化配置方法。在负荷端,构建了一种动态分时电价机制,对峰谷时段进行了动态划分,在引入替代弹性的基础上,以负荷与可再生能源发电差值累计和最小为优化目标,同时考虑用户参与需求响应的满意度,对动态分时电价中的峰谷电价进行寻优,计算需求响应后的负荷;在源端,考虑到水风之间的互补效应,提出了一种互补度评价指标,并在计及需求响应参与的基础上,建立了以年运营收益和水风互补度为目标函数的优化配置模型。采用改进粒子群算法结合目标规划法求解,仿真结果表明,将价格型需求响应应用到微电网优化配置中,能够将源-荷两侧有效结合,提高可再生能源消纳水平,在保证用户利益的同时提高微电网经济性。

风水互补微电网的功率波动节能控制数学建模

在对风水互补微电网的功率波动节能控制数学建模方法的研究过程中,采用当前的算法进行建模时受到大量的外界因素干扰,存在功率波动节能控制效果不佳的问题。为此,提出了一种基于功率曲线算法的风水互补微电网的功率波动节能控制数学建模方法。该方法针对运行的风水互补微电网系统进行分析,先计算出系统在不同自然条件下所需要的发电最大功率,依据系统在不同条件下对功率的需求设置2条或多条发电机机外特性曲线,在此基础上将风水互补微电网的功率波动节能控制问题转换为发电机与其功率平衡控制的问题,在保证负荷需求的基础上,以最大化利用风能和水能为原则,以整个系统的运行发电成本最低为目标建立风水互补微电网的功率波动节能控制数学模型。实验仿真证明,基于功率曲线算法的风水互补微电网的功率波动节能控制数学建模方法建模精确度高,鲁棒性强。

加强上海地区工程勘察中的水文地质工作

随着上海工程建设类型的增多,有必要强化岩土工程勘察中的水文地质工作,包括单元体划分,地下水位量测和水文地质边界的分析等。尤其是有关埋藏较浅的"微承压含水层"的工作。

黄色配镶钻石中合成钻石的鉴定

小颗粒黄色合成钻石常会与天然黄色钻石混合出现在批量裸石中或是作为配石出现在各种镶嵌饰品中。近期,笔者在日常检测中,发现一枚祖母绿戒指配镶的263粒黄色钻石中混有合成钻石,为了探索镶嵌中的小颗粒黄色合成钻石与天然钻石的鉴别方法,笔者对所有的黄色配镶钻石做了尽可能的详细测试,包括显微镜下内部特征观察、不同能量下的紫外荧光和磷光观察(普通的宝石荧光灯、GV5000、DiamondView^(TM))、显微红外吸收光谱以及光致发光光谱等测试。分析结果表明,其中7粒钻石为高温高压合成钻石,其红外吸收光谱显示均为纯Ib型,不含聚合氮,不含任何与氢有关的吸收峰,而其余的天然黄色钻石主要为IaA-Ib或Ib-IaA型,含有与氢有关的吸收峰(1 405,3 107cm^(-1)等)或含有与孤氮有关的吸收峰(1 352,1 358cm^(-1)等),此外合成钻石荧光较强,颜色为亮绿色,而天然钻石荧光则很弱,所有的合成钻石都可以检测到弱的与镍有关的883/884nm双发光峰。因此根据显微红外吸收光谱特征辅以荧光观察等方法,可以将镶嵌中的小颗粒黄色合成钻石与天然钻石区分开来。