浅谈电力系统继电保护

城市电网配电系统由于其覆盖的地域极其辽阔、运行环境极其复杂以及各种人为因素的影响,电气故障的发生是不能完全避免的。在电力系统中的任何一处发生事故,都有可能对电力系统的运行产生重大影响。为了确保城市电网配电系统的正常运行,必须正确地设置继电保护装置。     

浅析35kV变电站直流系统改造方案

随着科技和管理的进步,变电站直流系统正朝着自动化和免维护的方向发展,对直流系统要求的不断提高使得直流系统的改造势在必行,本文从分析当前35kV变电站直流系统存在的问题入手,以此提出改造目标,并对直流系统的改造措施进行简要分析。     

110kV高压输电线路工程的技术要点分析

110kV高压输电线路是电力系统的重要组成部分,担负着输送和分配电能的任务,并联络各发电厂、变电站使之有效运行。近年来,对110kV高压输电线路工程的质量要求比过去更加严格、规范,而电力行业的建筑施工部分是一项多工种、多专业的复杂的系统工程,尤其是具有专业性强、施工难度大、建设周期短等特点。本文对110kV高压输电线路工程的技术要点进行了一些相关探讨。     

Spatial integration at multiple scales: rice markets in Madagascar

The dramatic increase in the price of rice and other commodities over the past year has generated new interest in how these markets work and how they can be improved. This article uses an exceptionally rich data set to test the extent to which markets in Madagascar are integrated across space at different scales of analysis and to explain some of the factors that limit spatial arbitrage and price equalization within a single country. We use rice price data across four quarters of 2000–2001 along with data on transportation costs and infrastructure availability for nearly 1,400 communes in Madagascar to examine the extent of market integration at three different spatial scales—subregional, regional, and national—and to determine whether non-integration is due to high transfer costs or lack of competition. The results indicate that markets are fairly well integrated at the subregional level and that factors such as high crime rates, remoteness, and lack of information are among the factors limiting competition.     

Dynamic betas for Canadian sector portfolios

The dynamic betas for ten Canadian sector portfolios using the Kalman filter approach are estimated herein and are found to be best described by a mix of the random walk (trend) and mean-reverting (cycle) processes. The relative importance of the trend and cycle components of sector betas is related to different sensitivities of the corresponding sectors to business cycles. Dynamic betas significantly increase the explanatory power of the market model, and particularly for the utilities sector. A dynamic hedging strategy using the one-step-ahead beta forecasts as the hedge ratios produces smaller hedging errors for every sector compared with the hedge ratios calculated from the alternative beta specifications.     

Do investors hold that they know? Impact of familiarity bias on investor’s reluctance to realize losses: Experimental approach

In this article we investigate the impact of familiarity bias on the individual investor’s reluctance to realize losses. Our experimental approach reveals a strong correlation between familiarity and disposition effect. We conducted 714 tests in which different respondents could sell stocks of two types – winners and losers. One group of respondents “owned” familiar assets and another group operated anonymous portfolios. The results of the experiment show that an individual investor’s tendency to ride losers too long is more than twice as high in the case of unfamiliar stocks as it is when assets are familiar to the holder.     

关于750kV输变电工程造价管理的分析与研究

在电网建设中工程造价管理已成为电网建设管理的内容之一,本文作者通过对750kV输变电工程总体造价原因进行了分析,同时对750kV输变电工程造价管理措施做了阐述。     

Product line pricing in a vertically differentiated oligopoly

Abstract This paper examines the joint pricing decision of products in a firm’s product line. When products are distinguished by a vertical characteristic, those with higher values of that characteristic will command higher prices. We investigate whether, holding the value of the characteristic constant, there is an additional price premium for products on the industry and/or the firm frontier, that is, for the products with the highest value of the characteristic in the market or in a firm’s product line. We also investigate the existence of price premia for lower‐ranked products and other product line pricing questions. Using personal computer price data, we show that prices decline with the distance from the industry and firm frontiers, even after holding absolute quality constant. We find evidence that consumer tastes for brands is stronger for the consumers of frontier products (and thus competition between firms weaker in the top end of the market). There is also evidence that a product’s price is higher if a firm offers products with the immediately faster and immediately slower computer chip (holding the total number of a firm’s offerings constant), possibly as an attempt to reduce cannibalization. Finally, a product’s price declines with the time it is offered by a firm, suggesting intertemporal price discrimination.     

10kV城区配电网安全隐患分析及预防对策

10 kV配电线路由于其拥有广泛的用途,在社会生产与生活中发挥着非常重要的作用,然而却因为其没有杜绝安全隐患而常常出现事故。文章根据各相关单位配电网络的实际运行状况,分类统计并分析了近几年间所发生的10 kV配电运行事故,指出了存在的安全隐患,并提出了预防对策,这有利于提高配电网管理水平。     

110kV线路单相接地故障保护整定配合

本文在分析变压器中性点间隙保护的基础上,探讨了110kV线路接地时的线路及主变保护动作关系,提出了切实可行的解决措施。