光伏发电的最大功率跟踪算法比较

最大功率点跟踪是提高光伏发电系统使用效率的有效途径之一,本文详述了目前国内外的常用的自寻优算法及非自寻优方法的原理和特点,并针对几种方法的优缺点进行了分析比较。     

一种最大功率点跟踪方法的研究

在国家相关政策和文件精神的扶持和鼓励下,太阳能光伏发电近年来发展快速,在一般太阳能光伏发电中,都会涉及最大功率点跟踪。文章将研究和论述一种太阳能最大功率点跟踪的方法,并通过实验检测其有效性。     

浅谈功率因数与供电效率的关系

在交流电路中,由电源供给负载的电功率有有功功率和无功功率两种.有功功率是保持用电设备正常运行所需的电功率.无功功率比较抽象,它不对外做功,但是只要有电磁线圈的电气设备,就要消耗无功功率.文章介绍了影响功率因数的主要因素和提高功率因数的几种方法,从理论上分析了提高功率因数对于节约电能、降低损耗、提高输配电设备的供电能力方面的数量关系.     

浅谈功率因数与供电效率的关系

在交流电路中,由电源供给负载的电功率有有功功率和无功功率两种。有功功率是保持用电设备正常运行所需的电功率。无功功率比较抽象,它不对外做功,但是只要有电磁线圈的电气设备,就要消耗无功功率。文章介绍了影响功率因数的主要因素和提高功率因数的几种方法,从理论上分析了提高功率因数对于节约电能、降低损耗、提高输配电设备的供电能力方面的数量关系。     

基于风力发电的最大功率跟踪控制研究

文章以直驱永磁同步风力发电机组为对象,建立了包括风力机模型、传动系统模型和发电机模型的D-PMSG数学模型,提出了风力发电机转速控制最大功率追踪算法和桨距角控制策略。运用PSCAD/EMTDC建立D-PMSG仿真模型,对风速阶跃变化时机组运行情况进行了仿真,结果验证了该模型的合理性及控制策略的正确性和可行性。     

基于多断面控制法的在电力系统极限传输功率的计算方法

研究了一种基于多断面控制法的极限传输功率计算方法,并在某省电网的运行实际中验证了该计算方法的优越性。     

如何选择匹配的空调器功率

购买空调器时,如何估算自己房问所需的制冷量从而决定选多大的功率呢?要考虑的主要是房间面积的大小,门窗、外墙的方向,电气设备以及居住人数等。下面就这几方面因素作一大概的计算。 ①每平方米面积的房间所需制冷量约为120瓦。如果房间在顶楼或西晒则所需稍大一点,如果房间密封性能较好则所需制冷量可稍小一点。 如房间有窗,则所需制冷量要按其方向而定,东面窗所需制冷量约为150W/m~2(窗户面积),西面窗所需制冷量约为280W/m~2,北面窗所需制冷量约为     

混凝土泵车动力系统功率节能匹配的研究

通过对混凝土泵车的动力系统进行特性分析,找出了混凝土泵车燃油利用率较低的原因。通过大量的试验,对试验数据进行对比分析,得出了发动机转速与主泵流量的匹配区间,并编写了相关程序实现了相关匹配。最后通过实际泵送实验表明,利用这种方法进行功率匹配,对提高泵车燃油效率有显著成效。     

以隔离变压器作负载的变频器功率考核技术

文章针对常规负载的优缺点,从保证测试质量、提升测试效率、降低作业门槛、节约设备和人力资源投入成本、节能减排等方向出发,为业界提出一套较为合理有效的变频器功率考核试验系统及其方法。同时,结合笔者多年从事变频器测试技术工作积累的经验进行验证和分析,为合理选择变频器功率考核试验方法和测试系统,提供一套优选的参考和指导。     

试论通讯传输与地图信息传输的异同

文章通过分析通讯传输和地图信息传输的特点，得出通讯传输与地图信息传输的异同，以借鉴通讯传输的优点来作为思路，思考提高地图信息传输效率的方向。     

The efficiency of Spanish arable crop organic farms,a local maximum likelihood approach

The methodologies that have been used in existing research to assess the efficiency with which organic farms are operating are generally based either on the stochastic frontier methodology or on a deterministic non-parametric approach. Recently, Kumbhakar et al. (J Econom 137:1–27, 2007) proposed a new nonparametric, stochastic method based on the local maximum likelihood principle. We use this methodology to compare the efficiency ratings of organic and conventional arable crop farms in the Spanish region of Andalucía. Nonparametrically encompassing the stochastic frontier model is especially useful when comparing the performance of two groups that are likely to be characterized by different production technologies.

Maximal asymptotic power and efficiency of two-sample tests based on generalized U-Statistics

In this article a systematic study is given of the asymptotic behavior of two-sample tests based on U-Statistics with arbitrary antisymmetric kernels . Besides the investigation under the hypothesis and under fixed alternatives we determine the local power as a function of as well as its maximizing value _opt. Moreover formulas for the asymptotic relative efficiency ARE(₂,₁) of the ₂-test with respect to the ₁-test are derived. It turns out that _opt also yields the most efficient test in the sense that ARE(_opt,)1 for all (admissible) kernels .     

A multi-division efficiency evaluation of U.S. electric power companies using a weighted slacks-based measure

Prior to the 1990s, the electric power industry was highly regulated across the world. Under a liberalization policy to open markets and to grow competition commenced in the early 1990s, efficient management has become a necessity for companies in this industry. The current study examines the divisional efficiencies of multi-functional, vertically integrated companies seeking to optimize their overall management efficiency. For this purpose, divisional cost data are used as input into a slacks-based measure (SBM) model. This provides divisional efficiency indices based on slacks, as well as one for the larger firm-level management function. Further, given the important role of cost structure, we introduce a modified SBM, named the weighted SBM (WSBM), which directly incorporates division-specific weights into the objective function. Results reveal that the power generation divisions of the companies studied have significant influence on the overall cost, whereas the impact of the other four divisions - transmission, distribution, sales and general administrative - is limited.     

南方电网区域内输煤输电经济性比较研究

近年来随着环保要求的提升、发电煤耗的降低以及特高压直流输电技术的发展等各种因素的变化,输电输煤比较研究的基础逐渐改变。文章对南方电网区域内煤炭资源两种输送方式进行经济性比较,力求为煤炭资源输送方式的合理配置和煤电优化布局提供参考依据,以取得良好的社会经济和环境等综合效益。     

Vertical separation of transmission control and market efficiency in the wholesale electricity market

This study examines how vertical separation of transmission control affects the wholesale market efficiency in the electric power industry. We analyze a unique regional electricity wholesale market in the U.S. where initially restructuring only occurred in the transmission sector. Following a commonly-used best dispatch model (Wolfram, 1999; Borenstein et al., 2002), we simulate competitive benchmark prices and compare with the best estimates available for actual prices to measure price-cost markups of the wholesale market. Empirical results demonstrate that the vertical separation of transmission control led to a significant increase in market markups in peak-load hours, documenting evidence of enhanced market power. Although we also find a reduction in the price-cost margin in low-demand hours, we reserve caution for this finding.     

电网规划中的输配电联合潮流计算的研究

随着智能电网建设步伐的不断加快,全电压序列规划已成为电网建设规划研究的重要课题。为了构筑安全可靠、节能经济的电网规划方案,结合大量文献资料和实际研究成果,提出了在电网规划设计平台中嵌入与电网实际相互的输配电联合潮流计算模块,以便规划设计人员及时准确的了解电网的实际情况,并进行详细的潮流计算。     

Increase of electricity price and energy efficiency: analysis using the macroeconomic interindustry model of Taiwan

From 2012 to 2013, the price of electricity in Taiwan increased by 19.78%. This large increase forced producers to invest in improving electricity efficiency. In this paper, the macroeconomic interindustry model of Taiwan (MEIT) is developed to study the economic effects of high electricity prices and consequential improvement in energy efficiency. MEIT describes the structure of 47 industries, from both real and price-income approaches. To resolve inconsistent data, RAS is employed. A technical model is also integrated to consider technical feasibility, which offsets the usual shortcomings of technological analysis in an economic model. The iron and steel industry is taken as a case study. Estimated results indicate that higher electricity prices negatively affect Taiwan’s economy. However, improving energy efficiency can reduce some of this effect.     

A note on the maximum deviation of the scale-contaminated normal to the best normal distribution

In this paper we consider the case of the scale-contaminated normal (mixture of two normals with equal mean components but different component variances: (1−p)N(μ,σ²)+pN(μ,τ²) with σ and τ being non-negative and 0≤p≤1). Here is the scale error and p denotes the amount with which this error occurs. It's maximum deviation to the best normal distribution is studied and shown to be montone increasing with increasing scale error. A closed-form expression is derived for the proportion which maximizes the maximum deviation of the mixture of normals to the best normal distribution. Implications to power studies of tests for normality are pointed out. Received May 2001     

论火电厂锅炉给粉机不同运行方式对锅炉燃烧效率的影响

对大型火力发电厂而言,锅炉燃烧效率的高低直接影响到整个机组的经济性。文章通过实验,探讨了锅炉给粉机在不同运行方式下对锅炉效率的影响,从而指导我们在日常运行中优化给粉机配置,提高锅炉燃烧效率。     

Small is beautiful: Implications of reliability and statistical power for testing the efficacy of HR interventions

The development of optimal human resource practices is often contingent on the accurate statistical testing of potential interventions. Testing the efficacy of HR interventions can be enhanced by taking additional measures to improve statistical power, but the traditional means of increasing power through sample size are often beyond the cost and ability of HR professionals to pursue. This article, therefore, focuses on measurement procedures as an alternative way to increase statistical power for detecting HR intervention effects. Selection of reliable and appropriate measures and subsequent instrumentation are examined as efficacious and cost‐beneficial techniques that can be employed during the planning and designing stage of a study for augmenting statistical power to optimize business decision making. © 2012 Wiley Periodicals, Inc.