Resilence Control of DC Microgrid Integrated with Multi-Nanogrids Considering Connected-Islanded States

In this paper, a DC microgrid (DCMG) integrated with a set of nano-grids (NG) is studied. DCMG exchanges predetermined active and reactive power with the upstream network. DCMG and NGs are coordinately controlled and managed in such a way the exchanged P-Q power with external grid are kept on scheduled level following all events and operating conditions. The proposed control system, in addition to the ability of mutual support between DCMG and NGs, makes NGs support each other in critical situations. On the other hand, in all operating conditions, DCMG not only feeds three-phase loads with time-varying active and reactive power on the grid side but also injects constant active power into the grid. During events, NGs support each other, NGs support DCMG, and DCMG supports NGs. Such control strategies are realized by the proposed control method to increase resilience of the system. For these purposes, all resources and loads in DCMG and NGs are equipped with individual controllers. Then, a central control unit analyzes, monitors, and regularizes performance of individual controllers in DCMG and NGs. Nonlinear simulations show the proposed model can effectively control DCMG and NGs under normal and critical conditions.

One-Pot Synthesis of Axially and Centrally Chiral A-type Nanogrids

A novel type of A-type nanogrids(AGs)with axial and central chirality was synthesized via Friedel-Crafts gridization of thiophenes and difluorenyl biaromatic derivatives,yielding 9%-30%.Additionally,the effect of stereoisomers of 1,1'-binaphthyl difluorenols(BINDFOH)was investigated to demonstrate that R/S-BINDFOH is more advantageous for the synthesis of AGs than Mix-BINDFOH.Furthermore,tests on OFET memory devices showed that AGs have a larger storage window,indicating potential for data storage applications.

Optimal sizing of PV and battery-based energy storage in an offgrid nanogrid supplying batteries to a battery swapping station

Nanogrids are expected to play a significant role in managing the ever-increasing distributed renewable energy sources. If an off-grid nanogrid can supply fullycharged batteries to a battery swapping station(BSS)serving regional electric vehicles(EVs), it will help establish a structure for implementing renewable-energyto-vehicle systems. A capacity planning problem is formulated to determine the optimal sizing of photovoltaic(PV) generation and battery-based energy storage system(BESS) in such a nanogrid. The problem is formulated based on the mixed-integer linear programming(MILP)and then solved by a robust optimization approach. Flexible uncertainty sets are employed to adjust the conservativeness of the robust optimization, and Monte Carlo simulations are carried out to compare the performance of the solutions. Case studies demonstrate the merits of the proposed applications and verify the approach.

Design of protection and control scheme for hybrid nanogrid

Nanogrid is “The new ray of hope” for people living in remote isolated locations as well as where power supply reliability is poor. A nanogrid is a small power capacity distribution system with the ability to operate standalone or with a utility grid. It consists of local power production supplying local loads and energy storage systems. In this paper, an innovative inverter design is presented, which converts the power in a single stage. It is superior to the traditional two-stage inverter system and can supply hybrid loads (AC and DC loads) with a single input. System AC and DC bus voltages are regulated under both steady-state and dynamic load variation conditions in the nanogrid. Simulation results are presented which confirm the suitability of the inverter and its control strategy for a hybrid nanogrid system.

Hybrid Renewable Energy Resources Management for Optimal Energy Operation in Nano-Grid

Renewable energy resources are deemed a potential energy production source due to their cost efficiency and harmless reaction to the environment,unlike non-renewable energy resources.However,they often fail to meet energy requirements in unfavorable weather conditions.The concept of Hybrid renewable energy resources addresses this issue by integrating both renewable and non-renewable energy resources to meet the required energy load.In this paper,an intelligent cost optimization algorithm is proposed to maximize the use of renewable energy resources and minimum utilization of non-renewable energy resources to meet the energy requirement for a nanogrid infrastructure.An actual data set comprising information about the load and demand of utility grids is used to evaluate the performance of the proposed nanogrid energy management system.The objective function is formulated to manage the nanogrid operation and implemented using a variant of Particle Swarm Optimization(PSO)named recurrent PSO(rPSO).Firstly,rPSO algorithm minimizes the installation cost for nanogrid.Thereafter,the proposed NEMS ensures cost efficiency for the post-installation period by providing a daily operational plan and optimizing renewable resources.State-of-the-art optimization models,including Genetic Algorithm(GA),bat and different Mathematical Programming Language(AMPL)solvers,are used to evaluate the model.The study’s outcomes suggest that the proposed work significantly reduces the use of diesel generators and fosters the use of renewable energy resources and beneficiates the eco-friendly environment.

二维TiO_2纳米网格对CdTe量子点的吸附性能

通过真空蒸镀和高温煅烧方法,从蝴蝶翅膀鳞片生物模板上复制二维TiO2纳米网格,采用SEM、EDS、TEM等对其进行了表征,分析了其对CdTe量子点的吸附性能。结果表明:用此方法可成功制备二维TiO2纳米网格,高温煅烧可以完全去除生物模板;TiO2纳米网格上形成了吸附较好的CdTe量子点,TiO2纳米网格比TiO2膜有更好的吸附性能。

直流纳电网中用于高频隔离的CLLC型双向直流变压器的模态分析与优化设计

新型的CLLC型双向直流变压器(CLLC bidirectionalDC-DC transformer,CLLC-BDCT)具有控制策略简单、转换效率较高等优势,已成为实现低压直流纳电网与低压电网间高频隔离的可选拓扑之一。但复杂的运行过程严重阻碍了CLLC-BDCT的研究以及应用。首先指出了现有CLLC-BDCT理论分析方法,即基波近似分析(fundamental harmonic approximation,FHA)方法的低精确性,然后提出对CLLC-BDCT进行详尽的模态描述及分析。比照FHA的分析结果,提出的模态描述及分析不但为CLLC-BDCT工作状态的多样性提供理论支撑,而且能够精确预测其运行行为和重要特性。在此基础上,系统分析CLLC-BDCT的谐振网络参数与逆变开关管的零电压开通、直流电压增益及导通损耗的相关联性,阐明谐振网络参数对CLLC-BDCT闭环控制稳定性和运行效率的影响,进而提出一种CLLC-BDCT谐振参数的优化设计方法。最后,搭建一台380V输入,1.6k W、380V输出的CLLC-BDCT实验样机,实验结果验证了提出的运行模态描述分析结果及谐振参数优化设计方法的正确性。

模块化直流纳米电网即插即用控制策略

针对未来智能楼宇和家庭的供电需求,提出新型分布式纳米电网的组网结构,主要包含新能源发电模块、储能模块、并网模块、负载模块等.针对直流纳米电网的模块化运行、负载切换频繁的需求,提出基于直流母线电压信号的新型控制策略,实现直流纳米电网内各个模块的即插即用功能.针对多模块协同工作时产生的谐振问题,采用在电流反馈回路中增加低通滤波环节的方法保证在模块接入退出时直流母线电压的稳定.利用Matlab软件的Simulink平台搭建仿真模型并进行系统仿真,仿真结果表明所提控制策略的有效性、可靠性.

考虑需求响应的纳网双向定价斯坦伯格博弈模型

新能源发电和负荷需求的波动性使得纳网内能源盈馀不同,从而影响本地新能源消纳水平和运行成本.本文针对纳网内暖通空调潜在的热弹性调节能力,阐述了一种基于用户舒适度偏好和环境因素的需求响应和双向定价策略,来优化纳网与公共管理中心间的能源双向交易及时均收益.所构建的双层交易随机优化模型中由于存在不确定参数和时间耦合温度队列使得长期优化问题求解复杂.为此设计了一种基于李雅普诺夫优化方法的松弛形式对原问题进行时间解耦,重构主从博弈框架来刻画参与者能量交易决策间的相互影响关系,并进一步对博弈均衡点的存在与唯一性给出严格的证明.在此基础上提出了一种优化响应算法使得决策者间能以较少的信息交换达到博弈均衡.最后通过仿真实验验证了该能量管理算法的有效性.

直流纳网互联运行的在线能量管理方法

针对直流纳网互联形成的纳网群,提出一种在线能量管理方法,在纳网内部层面与纳网交互层面实现能量流控制。基于李雅普诺夫优化理论,构建虚拟储能队列,提出以提高光伏替代率与保证队列稳定性为目标的数学模型,将能量管理问题解耦为每个时刻的线性规划问题,不依赖系统中的未来信息,只需获取当下时刻的信息即可对纳网之间的交换电量做出实时决策。通过实际采集的用户负荷及光伏数据构造了仿真算例,结果验证了所提能量管理方法在满足纳网用户负荷需求的同时,有效地提高了可再生能源在直流纳网群中的消纳。同时,测试结果表明该算法决策时间较短,能满足系统的实时性要求。

有机纳米环/格的研究进展

径向共轭的碳纳米环作为碳纳米管的纳米片段,在合成化学、立体化学、超分子化学和材料科学领域引起了极大的关注.从几何结构角度来看,纳米环的结构分为单环纳米环和多环纳米环.其中,单环纳米环的构建模块主要有苯或多环芳烃以及大环,与以苯或多环芳烃为模块构造的单环纳米环相比,以大环为构建模块的单环纳米环和多环纳米环不仅具有特殊的拓扑结构还具有较高的荧光量子产率、较大的空腔等特点.目前这类具有拓扑结构的纳米环分子在主客体掺杂、储能材料、多孔和有机光电材料等领域体现出重要的研究价值.因此本综述将重点对卟啉类单环纳米环、“8”字型纳米环、纳米格以及更复杂的碳纳米笼的合成方法进行全面的综述.