Modelling and management of smart microgrid for rural electrification in sub-saharan Africa: The case of Nigeria

Access to electricity is still a challenge in many parts of sub-Saharan Africa. In Nigeria, over 70% of the rural dwellers do not have access to electricity. The purpose of this paper is to examine the potential of a smart microgrid for off-grid rural electrification in Nigeria. A combination of design thinking and model-based design methodology is employed to select a suitable microgrid configuration and to develop a smart microgrid model. A system consisting of a solar photovoltaic array, battery energy storage and a diesel generator is selected, and the model is developed in Simulink. Demand data from 10 rural communities in Nigeria are used to validate the performance of the model and the potential for demand management is considered. The use of energy efficient light bulbs is found to reduce the peak electricity demand of the case study communities by 42 to 76%. Combining the proposed system with the use of LED bulbs makes the system to have 56 to 81% less net present cost than a system with a diesel generator alone and incandescent light bulbs. The proposed smart microgrid is found to be more suitable for off-grid rural electrification in Nigeria than diesel generators which are currently used for off-grid electrification in Nigeria.     

QD10B-G2型1 000 kW燃气轮机发电车及其应用

北京电力公司,在全国电力系统中率先应用了当前最先进的燃气轮机发电技术,并设计定制了首台1 000 kW燃气轮机发电车.该型发电车的整体技术指标和性能、各项功能匹配、全部辅助设备等均达到了先进技术应用的完美结合,对今后电力系统的大功率发电车技术的应用和推广起到了很好的示范效果.文章介绍了首台1 000 kW燃气轮机发电车的结构特点,以及发电东的实际应用情况和技术发展方向.     

千瓦级熔融碳酸盐燃料电池组

论述了千瓦级熔融碳酸盐燃料电池组制备及组装工艺中双极板组合件、高温粘结剂、隔膜原位制备、制紧力、热量管理等技术。采用高温粘结技术制备双极板组合件 ,并在电池组启动时原位制备隔膜。由 5 2个单电池串联组成的电池组在65 0℃操作温度 ,0 .5MPa压力下 ,最大输出功率达到 10 2 5 .48W。用此高温粘结技术与湿密封相结合 ,使电池组的操作压力可达到 0 .5MPa。     

Metal-carbonate formation from ammonia solution by addition of metal salts—An effective method for CO2 capture from landfill gas (LFG)

The absorption of CO₂ from LFG in different weight concentration ammonia solution and metal salts (Zinc and Barium) is investigated in this study. Addition of metal salts results in useful metal carbonates when LFG is passed through the solution. Barium salts show a better potential of removing CO₂ as compared to Zinc salts. Addition of Barium salts to ammonia solution results in a new absorbent as no study has been focused on it till date. Also metal salts are added to alkaline wastewater which not only decreases the pH of the wastewater but also useful metal carbonates are obtained from wastewater when LFG is passed through it. Different parameters like CO₂ loading, reaction rate and change in pH are investigated. Formation of carbonates is proved by using SEM and XRD analysis. Raman spectroscopy was performed on the discarded liquid after removal of carbonates to understand the formation of bicarbonates, carbonates and carbamates.     

150kW备用发电机加热装置与自启动装置的技术改造

集宁供电分局使用的150 kW备用发电机为柴油发电机组,冬季低温使用时启动困难,而且启动后采用人工投入的方法,导致故障停电时间长,无法满足供电可靠性要求。为缩短故障停电时间,对150 kW备用发电机加装加热装置和自启动装置。实践证明,150 kW备用发电机加装加热装置和自启动装置后,耗油量小,启动速度快,降低了工作人员的工作量,应用效果良好。     

Stationary Fuel Cells at Work – An Interim Report

Different fuel cell systems, in various numbers, have been installed and run at customers' sites using natural gas. Operational results from these field tests are presented, which demonstrate that several fuel cell systems can be used successfully to generate heat and electricity. Improved reliability and cutting costs are the most urgent challenges for commercialisation.     

Regulatory framework and business models for charging plug-in electric vehicles: Infrastructure,agents, and commercial relationships

Electric vehicles (EVs) present efficiency and environmental advantages over conventional transportation. It is expected that in the next decade this technology will progressively penetrate the market. The integration of plug-in electric vehicles in electric power systems poses new challenges in terms of regulation and business models. This paper proposes a conceptual regulatory framework for charging EVs. Two new electricity market agents, the EV charging manager and the EV aggregator, in charge of developing charging infrastructure and providing charging services are introduced. According to that, several charging modes such as EV home charging, public charging on streets, and dedicated charging stations are formulated. Involved market agents and their commercial relationships are analysed in detail. The paper elaborates the opportunities to formulate more sophisticated business models for vehicle-to-grid applications under which the storage capability of EV batteries is used for providing peak power or frequency regulation to support the power system operation. Finally penetration phase dependent policy and regulatory recommendations are given concerning time-of-use pricing, smart meter deployment, stable and simple regulation for reselling energy on private property, roll-out of public charging infrastructure as well as reviewing of grid codes and operational system procedures for interactions between network operators and vehicle aggregators.     

Experimental analysis of the performance of the air supply system in a 120 kW polymer electrolyte membrane fuel cell system

For analyzing the performance of 120 kW polymer electrolyte membrane fuel cell (PEMFC) system and its air supply system, an air system test bench was built, then applied on a 120 kW PEMFC system test bench composed of air supply subsystem, hydrogen supply subsystem, stack, cooling subsystem and electronic control subsystem. The strategy composed of feedforward table and Piecewise proportional integral (PI) feedback control strategy is employed to regulate the flow rate and pressure of air supply system. Firstly, the air compressor map and the mapping relationship between the speed of air compressor, opening of back-pressure valve and stack current are obtained by carrying out experiments on the PEMFC air system bench. Then, the max output performance, steady-state performance, the startup performance, the dynamic response abilities of PEMFC system are tested, respectively. During the experiments, performances under different test conditions were analyzed by comparing parameters such as voltage inconsistency, average voltage, minimum voltage, voltage range, net power of the PEMFC system, and stack power. The test results show that the air supply system can provide qualified flow rate and pressure for the PEMFC stack. The peak power of the stack is 120 kW and net power of the system is 97 kW when the current is 538 A. The response time from rated net power to idle net power is 12 s and from idle net power to rated net power is 23 s. The overshoot of average voltage and minimum voltage in the process of increasing load is both 0.01 V, which are 0.015 V and 0.02 V lower than that when the load is decreased, respectively. The dynamic response speed and stability of the PEMFC system in the process of decreasing the load are better than those in the process of increasing the load.     

Experimental analysis of an ejector for anode recirculation in a 10 kW polymer electrolyte membrane fuel cell system

For analyzing ejector's performance in the system, an ejector for a 10 kW polymer electrolyte membrane fuel cell (PEMFC) system was first designed, manufactured, and a 10 kW PEMFC system bench was built up. A proportional valve and PI pressure feedback control method were adopted to control the hydrogen supply and anode inlet pressure. During the test, performances between dead-ended anode (DEA) mode and ejector mode were compared. Ejector's performances in the system, i.e., volume flow recirculated ratio, difference pressure, dynamic responses of primary pressure, anode inlet pressure, and recirculated gas flow rate during the purge process and current variation condition, were investigated. The results show that pressure adjustment is accurate, continuous, and fast using the proportional valve and PI pressure feedback control method. The hydrogen consumption rate in the ejector mode can reduce from 5% to 10% compared with the rate in the DEA mode except for the stack current 5 A and 10 A conditions. For better water removal out of the anode channel in ejector mode, the maximum stack power increases from 5.11 kW (DEA mode) to 9.56 kW (ejector mode). Anode pressure surge caused by the purge valve switching enhances the ejector's recirculated performance significantly.     

煤田绳索取芯深孔钻探设备的选择与应用

探讨了煤田绳索取芯深孔钻探设备选用XY-6B立轴岩芯钻机、BW-320泥浆泵、GF-120 kW柴油发电机组及ZT-17A加强型四脚钻塔等,开展了深孔施工技术研究,指出煤田绳索取芯深孔钻探设备可降低钻探直接成本、能占领深孔钻探市场,对提高福建省121队的核心竞争力,保持绳索取芯钻进技术领先水平具有重要意义。