Aggregator-based demand response mechanism for electric vehicles participating in peak regulation in valley time of receiving-end power grid

With the increase in the power receiving proportion and an insufficient peak regulation capacity of the local units, the receiving-end power grid struggles to achieve peak regulation in valley time. To solve this problem while considering the potential of the large-scale charge load of electric vehicles(EVs), an aggregator-based demand response(DR) mechanism for EVs that are participating in the peak regulation in valley time is proposed in this study. In this aggregator-based DR mechanism, the profits for the power grid’s operation and the participation willingness of the EV owners are considered. Based on the characteristics of the EV charging process and the day-ahead unit generation scheduling, a rolling unit commitment model with the DR is established to maximize the social welfare. In addition, to improve the efficiency of the optimization problem solving process and to achieve communication between the independent system operator(ISO) and the aggregators, the clustering algorithm is utilized to extract typical EV charging patterns. Finally, the feasibility and benefits of the aggregator-based DR mechanism for saving the costs and reducing the peak-valley difference of the receiving-end power grid are verified through case studies.

VARIABILITY OF BUILDING SIMULATION RESULTS DEP ENDING ON SELECTED WEATHER FILES AND CONDITIONING SET POINTS-A CASE STUDY FOR A RESIDENTIAL BUILDING IN VICTORIA,AUSTRALIA

Building simulation is a powerful way to evaluate the performance of a building.The quality of simulation results however strongly depends on the accuracy of simulation input data.Especially for weather data files and occupant behaviour it is difficult to obtain accurate data.This paper evaluates the variability of building simulation results with regards to different weather data sets as well as different heating and cooling set points for a residential building in Victoria,Australia.Thermal comfort accord-ing to ASHRAE Standard 55,final energy consumption and peak cooling and heating loads are assessed.Simulations have been performed with Energy-Plus,and weather data for a multi-year approach have been generated with the software Meteonorm.The results show that different weather files for the same location as well as different conditioning set points can influence the results by approximately a factor of 2.

Direct Analytical Method to Calculate Photopeak Efficiency and Photopeak Attenuation Coefficient of NaI(Tl) Well-Type Detector

In this paper full-energy peak (photopeak) efficiency and photopeak attenuation coefficient of 3'' × 3'' NaI(Tl) well-type scintillation detector were calculated using gamma-rayisotropic radiating point sources (with photon energy: 0.245, 0.344, 0.662, 0.779, 0.964, 1.1732, 1.333 and 1.408 MeV) placed outside the detector well. These energies were obtained from 152Eu, 137Cs and 60Co. The relations between the full energy peak efficiency and photopeak attenuation coefficients, were plotted vs. photon energy at different sources to detector distance, and it found that the full energy peak efficiency decreased by increasing the distance between the source and the detector.

A Parallel Search Genetic Algorithm Based on Multiple Peak Values and Multiple Rules

In this paper the Hamming distance is used to contr ol individual difference in the process of creating an original population, and a peak-depot is established to preserve information of different peak-points. So me new methods are also put forward to improve optimization performance of genet ic algorithm, such as point-cast method and neighborhood search strategy around peak-points. The methods are used to deal with genetic operation besides of cr ossover and mutation, in order to obtain a global optimum solution and avoid GA ’s premature convergence. By means of many control rules and a peak-depot, the new algorithm carries out optimum search surrounding several peak-points. Alon g with evolution of individuals of population, the fitness of peak-points of pe ak-depot increases continually, and a global optimum solution can be obtained. The new algorithm searches around several peak-points, which increases the prob ability to obtain the global optimum solution to the best. By using some example s to test the modified genetic algorithm, the results indicate what we have done makes the modified genetic algorithm effectively to solve both of linear optimi zation problems and nonlinear optimization problems with restrictive functions.

基于峰值比拟合匹配的时差式气体超声波流量计

时差式气体超声波流量计的回波信号在气体中传播时能量衰减严重,且存在着不同程度的幅值晃动问题。因此如何在幅值晃动的气体回波信号中确定特征点,以准确测量回波信号渡越时间及其顺、逆流渡越时间差,是当前时差式气体超声波流量计信号处理方法的主要研究热点。该文基于超声回波信号的数学模型,研究构建了一种基于峰值比拟合匹配的信号处理方法,利用拟合指标来筛选符合匹配条件的波形。并且通过实际数据验证了该方法的有效性和优越性。

床旁即时超声测量动脉峰流速呼吸变异度评价危重症患者容量反应性的临床价值

目的评估床旁即时超声(POCUS)测量动脉峰流速呼吸变异度(△Vpeak)评价危重症患者容量反应性的临床价值。方法回顾性选取川北医学院附属医院于2021年1月至2023年6月收治的100例危重症患者作为研究对象,所有患者均接受容量负荷(VE)试验,根据患者容量反应性分为有反应组[容量负荷后心脏每搏量(SV)增加≥15%,n=56]与无反应组(心脏指数增加<15%,n=44)。容量负荷前后均对患者实施床旁即时超声测量及中心静脉压(CVP)、脉压变异率(PPV)检测,比较两组容量负荷前后△Vpeak[主动脉血流峰流速(△Vpeak-AO)、颈总动脉血流峰流速(△Vpeak-CA)、肱动脉血流峰流速(△Vpeak-BA)、股动脉血流峰流速(△Vpeak-FA)]、CVP、PPV指标,并绘制受试者工作特征(ROC)曲线分析△Vpeak对危重症患者容量反应性的预测价值。结果容量负荷前,有反应组患者的△Vpeak-AO、△Vpeak-CA、△Vpeak-BA、△Vpeak-FA以及PPV分别为(15.42±4.24)%、(14.24±3.24)%、(13.29±2.54)%、(12.35±2.24)%、(13.32±2.53)%,均高于无反应组[(10.93±4.63)%、(10.48±3.16)%、(9.48±2.68)%、(7.84±2.16)%、(9.35±1.27)%],差异均有统计学意义(P<0.05),两组患者CVP比较差异无统计学意义(P>0.05);容量负荷后,有反应组与无反应组各项△Vpeak指标与PPV、CVP比较差异均无统计学意义(P>0.05)。△Vpeak-AO、△Vpeak-CA、△Vpeak-BA、△Vpeak-FA对危重症患者容量反应性敏感度、特异度及曲线下面积高于PPV。结论床旁即时超声测量△Vpeak能够有效预测危重症患者容量反应性,为临床诊断及治疗提供指导,具有较高临床价值。

一种 QAM星座点优化方法及性能分析

正交幅度调制(Quadrature Amplitude Modulation,QAM)是目前无线通信中大量应用的调制技术,其位于4个角的星座点易受链路的影响而导致较高误码率。提出了一种QAM星座点整形优化方法,并对整形优化后的QAM星座点性能进行了计算机仿真分析。以标准星座点为初始值,通过遗传算法逐步迭代,搜索出抗削峰的星座点,从而降低解调误码。仿真结果表明,相比标准QAM,整形优化后的星座点峰均比降低1 dB@1E-6,且在OBO=3.5 dB时有大约0.3 dB@SER=1E-3的解调增益提升。

基于多策略混合改进MVO算法的光伏多峰MPPT研究

光伏阵列的电功率输出在局部遮荫工况下具有多峰特性,且随外界环境的变化而变化.为实现高效电能输出,利用多元宇宙优化(MVO)算法在解决低维度、小规模优化问题中的突出优势进行最大功率点跟踪(MPPT),并融合多种策略对其存在的缺陷进行改进.采用拉丁超立方抽样策略初始化宇宙种群,并对按照轮盘赌策略随机交换的宇宙实施柯西变异,提高宇宙种群的多样性.同时引入莱维飞行式量子粒子群优化(QPSO)算法,且对虫洞存在概率及旅行距离率进行自适应调整,以增强算法的全局勘探及局部开发能力.Matlab仿真结果表明,相比其他算法,采用该算法的MPPT时间减少了45%以上,精度亦有所提高,从而具有更优的MPPT性能,可有效提高光伏发电效率.

基于改进布谷鸟搜索算法的光伏最大功率点跟踪策略

实际工程中,光伏阵列在随机变化的环境中会出现局部遮光的情况,从而导致光伏阵列的功率-电压特性曲线会呈现多峰值状态,传统的最大功率点跟踪(maximum power point tracking, MPPT)算法易陷入局部最优解,追踪速度和精准度无法得到满足。针对这一问题,提出一种基于布谷鸟搜索算法(cuckoo search algorithm, CS)和电导增量法(conductivity increment method, CI)结合的光伏MPPT算法,在算法前期利用布谷鸟搜索算法将大步长和小步长交替使用使得全局搜索能力增强,找到全局最大功率点所处区域附近;在后期,采用步长小、控制精度高的CI进行局部寻优,快速准确地锁定到最大功率点。在MATLAB/Simulink中搭建仿真模型,并与原始布谷鸟搜索算法和粒子群优化(particle swam optimization, PSO)算法进行比较。仿真结果表明,将CS与CI结合的算法使得收敛速度更快,精度更高,稳定状态时功率曲线的波动更小。

基于周期性最大功率点检测的风电机组功率备用控制方法

风电机组通常运行于最大功率输出模式,无法为受扰电网提供紧急功率支撑。稳态时预留部分出力可提高风电机组主动电网支撑能力,为此提出一种基于周期性最大功率点(MPP)检测的风电机组功率备用控制(PRC)方法。通过周期性执行最大功率点跟踪程序检测风电机组实时MPP,一旦检测到MPP即可确定PRC模式参考值并切换为直接功率控制。设置伪单调转速-机械功率曲线使风电机组稳定运行在超速功率备用点,并通过储能装置平抑MPP检测产生的峰值功率波动。仿真结果表明提出的控制方法在定风速和变风速情况下均可以准确控制检测风电机组MPP并实现PRC,并且使得风电机组一次调频效果优于传统PRC。

车联网中最小化峰值信息年龄的任务卸载策略

为解决车联网中数据密集型任务对信息新鲜程度极为敏感的问题,针对车路协同场景提出一种最小化峰值信息年龄策略。在所提策略中,将峰值信息年龄定义为任务更新间隔、传输时间以及等待时间三者之和的期望,将变量高度耦合的非线性优化问题转化为任务卸载比例和任务更新间隔两个子问题。在任务卸载比例问题中,证明最小峰值信息年龄的存在条件并获得最优卸载比例。通过内点罚函数法求解车辆任务更新间隔问题。给出两个子问题的交替迭代策略,实现全局车辆峰值信息年龄最小。数值仿真结果验证了所提策略在减少全局车辆峰值信息年龄方面的有效性。

酸洗脱灰处理对煤自燃倾向性的影响分析

煤自燃倾向性是矿井火灾预测的关键参数之一,受煤的化学成分、孔隙结构、官能团等多种自身理化性质的影响,酸洗脱灰处理可以有效去除煤中杂质,提高煤的纯度。为深入探究酸洗处理对煤自燃倾向的影响,采用2 mol/L的硫酸对煤样品进行酸洗处理。通过气相色谱、热分析及红外光谱等实验,将酸洗煤样品与原煤样品进行对比分析。结果表明,酸洗脱灰处理能够有效去除煤中赤铁矿等金属氧化物类矿物,以及高岭土等矿物。同时对煤中芳香类官能团的取代结构、含氧官能团中的羟基以及脂肪类官能团中的侧链结构等产生显著影响。与原煤相比,经处理的煤样品脱灰率为26.4%,交叉温度点由203.6℃变为205.5℃,热失重速率从11.27%/min降为10.21%/min,峰值温度由503.77℃升高为521.66℃,自燃倾向性降低,为酸洗后煤自燃的预测和防控提供了理论指导。

Electric Vehicle Charging Load Optimization Strategy Based on Dynamic Time-of-Use Tariff

Electric vehicle(EV)is an ideal solution to resolve the carbon emission issue and the fossil fuels scarcity problem in the future.However,a large number of EVs will be concentrated on charging during the valley hours leading to new load peaks under the guidance of static time-of-use tariff.Therefore,this paper proposes a dynamic time-of-use tariff mechanism,which redefines the peak and valley time periods according to the predicted loads using the fuzzy C-mean(FCM)clustering algorithm,and then dynamically adjusts the peak and valley tariffs according to the actual load of each time period.Based on the proposed tariff mechanism,an EV charging optimization model with the lowest cost to the users and the lowest variance of the grid-side load as the objective function is established.Then,a weight selection principle with an equal loss rate of the two objectives is proposed to transform the multi-objective optimization problem into a single-objective optimization problem.Finally,the EV charging load optimization model under three tariff strategies is set up and solved with the mathematical solver GROUBI.The results show that the EV charging load optimization strategy based on the dynamic time-of-use tariff can better balance the benefits between charging stations and users under different numbers and proportions of EVs connected to the grid,and can effectively reduce the grid load variance and improve the grid load curve.

拇指施力点对颈椎定点旋转手法安全性的影响

目的为手法治疗规范提供指引,提高颈椎定点旋转手法的可控性,降低治疗风险。方法采用前瞻性随机对照,招募62名Ⅰ、Ⅱ级颈痛患者,随机分成a、b两组,由同1名测试者行颈椎定点旋转手法,治疗a组时拇指作用在正中线旁2cm位置,治疗b组时拇指作用在正中线位置,用压力测量仪器测量记录手法过程中出现咔哒声响时拇指的峰值力。结果两组受试者的一般资料特征相比较,差异均无统计学意义(P>0.05)。a组拇指峰值压力低于b组,两组差异有统计学意义(P<0.05)。拇指峰值压力与年龄、体重、身高均呈负相关。结论在实施颈椎定点旋转手法时,鉴于拇指在作用于关节突时所产生的顶推力较为轻微,且其相对可控性较强,操作风险相对较低,因此,推荐优先选择关节突作为拇指的施力点。

经皮穴位电刺激内关穴对全麻诱导后低血压的预防作用

目的探究经皮穴位电刺激内关穴对全麻诱导后低血压的预防作用。方法前瞻性选择2022年4~10月在广州中医药大学深圳医院择期行全身麻醉气管插管下手术的80例患者进行研究,按照随机数表法分为观察组和对照组,每组40例。观察组患者于术前10 min开始接受经皮内关穴电刺激,持续30 min,对照组患者仅在同样部位连接电极但不予电刺激。分别于患者麻醉前10 min(T1)、麻醉后气管插管后3 min(T2)、30 min(T3)后记录两组患者血流动力学指标[心率(HR)、舒张压(DBP)、收缩压(SBP)、平均动脉压(MAP)],并比较两组患者治疗期间的羟胺用药情况、输液量和尿量情况;同时采用超声监测两组患者颈动脉情况,记录并比较颈动脉校正血流时间(FTc)及颈动脉峰流速呼吸变异度(ΔVpeak);术后随访24 h,比较两组患者的术后恢复情况。结果组间比较:T1时,两组患者的HR、DBP、SBP、MAP比较差异均无统计学意义(P>0.05),T2、T3时,观察组患者的HR、DBP、SBP、MAP明显高于对照组,差异均有统计学意义(P<0.05);组内比较:两组患者T3的HR、DBP、SBP、MAP明显高于T2,T2的HR、DBP、SBP、MAP明显高于T1,差异均有统计学意义(P<0.05)。组间比较:T1时,两组患者的FTc、ΔVpeak比较差异均无统计学意义(P>0.05),T2、T3时,观察组患者的FTc、ΔVpeak水平明显低于对照组,差异均有统计学意义(P<0.05);组内比较:两组患者T3的FTc、ΔVpeak明显高于T1,T2的FTc、ΔVpeak明显高于T2,差异均有统计学意义(P<0.05)。观察组患者的去间羟胺用药率为7.5%,明显低于对照组的47.50%,差异有统计学意义(P<0.05),但两组患者的输液量、尿量比较差异均无统计学意义(P>0.05);术后24 h,观察组患者的恶心呕吐、头晕的发生率分别为10.00%、2.50%,明显低于对照组的62.50%、15.00%,差异均有统计学意义(P<0.05),但两组患者的胸闷、呼吸困难发生率比较差异均无统计学意义(P>0.05)。结论经皮穴位电刺激内关穴能够有助于稳定患者麻醉期间的血流动力学,有效预防全身麻醉诱导后低血压,同时超声检测颈动脉血流指标有助于评估患者血容量情况,及时纠正容量不足,从而减少低血压发生率。

改进平均间隙法在某电厂沉降观测中的应用研究

用于检验基准网稳定性的平均间隙法在寻找不稳定点时存在过程复杂、计算量大、检验对象受平差基准影响等不足。为解决这些问题,提出一种结合密度峰聚类的改进平均间隙法,并应用于某火电厂沉降监测。应用情况表明,与传统平均间隙法相比,改进平均间隙法能够正确检验出不稳定点,计算复杂度低,检验效率更高,结果的可靠性更高。

APS在萧燃电厂机组中的应用

燃气-蒸汽联合循环机组作为电网调峰机组,具有启动快、燃烧效率高等特点,在我国电力生产行业中的地位日益提高。然而机组启停频繁,给安全运行带来一定的挑战。以萧燃电厂9F联合循环机组自动启停控制系统(APS)为例,对APS设计思想、结构和断点以及实现进行分析。研究表明APS能够实现机组从启动准备工作到燃气轮机、汽轮机启动到发电机并网带满负荷的一键功能,使得机组在启停过程中实现重要控制回路全程化、启动条件自优化、启停标准化、切换操作自动化和参数控制智能化,有效提高了机组启停的安全性、经济性。

基于虚拟仪器的曳引式电梯节能效果检测方法

为提高曳引式电梯的节能检测能力,文中提出一种基于虚拟仪器的曳引式电梯的节能效果检测方法。构建曳引式电梯的节能参数解析模型,结合非正弦激励损耗分析方法,得到感应电动机驱动曳引式电梯的能量分布关系。根据能量分布关系分析曳引式电梯的节能参数与剩余损耗算式之间的函数关系,采用简化静态Preisach模型推导出曳引式电梯的节能效果的偏置小磁滞参数。考虑偏置小磁滞融合参数,通过检测相电流峰值点获得曳引式电梯的功率损耗和电能增益参数,采用Energetic磁滞模型,得到交流曳引式电梯的电动机转矩信息参数,根据参数估计结果,实现对曳引式电梯的节能效果检测。实验结果表明,采用本文方法进行曳引式电梯节能效果检测的可靠性和检测性能较好,提高了曳引式电梯节能效果的可视化交互和管理能力。

基于机器视觉的玉米根茎导航基准线提取方法

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