Making sense of absolute measurement: James Clerk Maxwell,William Thomson,Fleeming Jenkin,and the invention of the dimensional formula

During the 1860s, the Committee on Electrical Standards convened by the British Association for the Advancement of Science (BAAS) attempted to articulate, refine, and realize a system of absolute electrical measurement. I describe how this context led to the invention of the dimensional formula by James Clerk Maxwell and subsequently shaped its interpretation, in particular through the attempts of William Thomson and Fleeming Jenkin to make absolute electrical measurement intelligible to telegraph engineers. I identify unit conversion as the canonical purpose for dimensional formulae during the remainder of the nineteenth century and go on to explain how an operational interpretation was developed by the French physicist Gabriel Lippmann. The focus on the dimensional formula reveals how various conceptual, theoretical, and material aspects of absolute electrical measurement were taken up or resisted in experimental physics, telegraphic engineering, and electrical practice more broadly, which leads to the conclusion that the integration of electrical theory and telegraphic practice was far harder to achieve and maintain than historians have previously thought. This ultimately left a confusing legacy of dimensional concepts and practices in physics.     

浅议电力企业降低线损率的措施

供电企业是为电力企业获取经济效益最直接的窗口。如何降低线损率,提高供电企业的经济效益,这对处在改革和发展过程中的电力企业是一个不小的挑战。降低线损率是提高电力企业经济效益的一个重要方面。文章通过对线损概念的提出、解释,分析了当前电网线损产生的主要原因,针对这些原因指出了降低线损率的管理措施和技术措施,最后提出合理降低线损率对节能减排的促进作用。     

Integrating time-series and end-use methods to forecast electricity sales

Two types of forecasting methods have been receiving increasing attention by electric utility forecasters. The first type, called end-use forecasting, is recognized as an approach which is well suited for forecasting during periods characterized by technological change. The method is straightforward. The stock levels of energy-consuming equipment are forecast, as well as the energy consumption characteristics of the equipment. The final forecast is the product of the stock and usage characteristics. This approach is well suited to forecasting long time periods when technological change, equipment depletion and replacement, and other structural changes are evident. For time periods of shorter duration, these factors are static and variations are more likely to result from shocks to the environment. The shocks influence the usage of the equipment. A second forecasting approach using time-series analysis has been demonstrated to be superior for these applications. This paper discusses the integration of the two methods into a unified system. The result is a time-series model whose parameter effects become dynamic in character. An example of the models being used at the Georgia Power Company is presented. It is demonstrated that a time-series model which incorporates end-use stock and usage information is superior—even in short-term forecasting situations—to a similar time-series model which excludes the information.     

State-space modelling of residential,commercial and peak demands

The potential use of state-space modelling is evaluated through comparison with the existing multivariate ARMA models currently in use at Georgia Power Company for forecasting its residential sales, commercial sales and peak demand.     

半导体变流技术的应用

本文通过实例论述半导体变流技术在工业电气化及自动化中的应用。     

电力市场环境下的输电阻塞管理

电力市场的开放,将不可避免地发生输电阻塞问题。为了确保电力系统的安全经济运行,需要对输电系统进行有效的管理。与传统的方法相比,现在的研究更强调在经济方面的重要性。本文对不同市场交易模式下的阻塞调度,及市场环境下阻塞成本的分摊进行了综述;最后对最新的研究方向做了分析。     

防坠落装置在高处作业上的应用

本文通过对输电线路杆塔防坠落装置的结构特点、基本原理、使用与维护、安全注意事项及存在问题与建议等方面进行阐述观点,为防坠落装置在高处作业的应用提供参考。     

A comparison of adaptive structural forecasting methods for electricity sales

This paper presents the results of a study to determine whether new forecasting technologies might be of use to electric utilities for sales forecasting up to 3 years into the future. The methods considered included ordinary least squares on dynamic structural models, autocorrelated error models, adaptive variance and adaptive parameter models. Overall, the more adaptive models performed best, but most of the methods proved vastly superior to simple least squares models which do not take dynamics into account.     

浅论责任法人机制

以西山煤电集团公司为例,从战略导向机制、责任落实机制、利益平衡机制、激励约束机制及综合保障机制5个方面,论述了企业实行责任法人机制的优势。     

覆盖率分布式发电对电力系统的影响分析

本文探讨了分布式发电对电力系统的设计、工程实施以及运行可靠性的要求,考察了分布能源的大规模应用对电力系统设计、安全运行的影响,并引用实例说明。同时,本文也展望了未来分布式发电在电力工业中的发展远景。