Minitab在分析发电负荷控制精度中的应用

针对发电负荷控制精度在生产中存在的问题,应用Minitab工具对发电负荷控制精度的影响因素进行分析,找出关键因素并加以改进。实践证明,实施效果显著。     

双细则考核下发电机组协调控制的优化研究

自动发电控制是我国电网功率调整与频率调整的重要手段,它承担着调节控制联络线交换功率、电网频率等重要任务,伴随电网负荷分配大多运用自动发电控制系统,发电机组必须在保证稳定性基础上,具有更灵活、更快的负荷响应。本文以某电厂由两台300MW发电机组成的机组为研究对象,重点分析发电控制系统的双细则考核下发电机组的协调系统存有的适应负荷问题,例如:对负荷响应的速度较慢、适应负荷滞后现象等,再参照燃烧系统设计特征和发电机组的设备构成特点,论证解决发电机组控制系统在负荷适应方面问题的措施和方法。     

基于光伏和柴油机组的用电系统经济性分析

由于并网光伏发电设备价格的持续下降和光伏发电补贴政策的实施,并网光伏发电系统应用逐渐广泛。从全生命周期角度出发,分析了并网光伏发电系统和柴油发电机组的单位电量发电成本组成和计算方法,然后以某用电系统为例,分析了并网光伏发电系统供电经济性,在电网缺失条件下柴油机组和光伏系统向备用负荷供电的经济性。分析表明,在计及补贴的情况下,并网光伏发电成本可低于工业销售电价,当柴油发电机组与光伏系统共同承担备用负荷时用电成本更低,可作为一种供电系统方案进行参考。     

生物质发电项目装机方案选择

目前生物质发电作为清洁高效的绿色环保项目,在全世界范围内都在大力推广发展和扶持。根据燃料情况、电负荷和热负荷情况,选择最合适的装机方案是最重要的环节。以山东电力工程咨询院有限公司设计的喀麦隆SUDCAM生物质发电工程为例,根据该项目的电负荷、供热负荷需求,通过不同装机方案的技术、经济比选,得出最适合本项目的装机方案,以期为相关工作者提供借鉴。     

中小型水电厂自动发电控制技术研究

与大型的水电站相比,我国的中小型水电站自动发电控制技术还比较落后,如果不加强这方面的建设,那么中小型水电厂自动发电控制技术将无法满足未来电力生产的要求。中小型水电厂使用自动发电控制技术时,要合理调节负荷、功率、频率这三个重要的数值。文章对中小型水电厂自动发电控制技术进行了研究。     

锅炉受热面结焦的因素探研

黑龙江华电富拉尔基发电有限公司,机组长时间高负荷运行时,出现锅炉受热面结焦问题,影响到机组带负荷,对锅炉安全运行带来一定影响。分析影响锅炉受热面结焦原因,找出解决结焦的运行措施,指导当前发电运行工作。     

热电厂煤耗指标偏高原因分析及对策

天富热电厂是热电联产企业,发电标准煤耗率与燃料性质、设备性能、热负荷大小及变化、与经济调度等因素有关。今年前两个月发电标准煤耗偏高,通过分析、判断、找出发电标准煤耗偏高的原因,并通过必要的方法使其减少,来提高管理水平,更好地实现节能降耗。     

节能减排调度环境下燃煤电厂发电成本分析

电力节能调度能够促进我国环境污染与能源紧张现状的缓解,节能减排调度可以改变以往传统发电调度形式有效减少污染物的排放,降低能源消耗,确保电力系统清洁、高效的运行。近年来,节能减排调度对发电企业要求不断提高,发电企业不仅要申报其污染排放与能源消耗,还要分析自身环境成本、能耗成本等,并根据这些制定发电价格。本文主要分析了某燃煤电厂动态成本及发电成本影响要求,构建成本要求计算模型与分析模型,分析机组负荷和发电成本的关系。     

水电站AGC/AVC控制简介

本文将介绍AGC/AVC基本功能、操作模式、自动开停机、有、无功功率负荷分配、频率和电压控制等。其中详细介绍在自动发电控制中的负荷分配和怎样躲避振动区、自动开停机三个方面内容。     

ASTM批准蠕变疲劳测试方法新标准

蠕变疲劳测试是模拟飞机发动机涡轮部件、核反应堆部件和矿物发电装置部件运行中的负荷和温度条件。随着对峰值功率需求量期间循环运行的要求越来越大，必须有可靠的蠕变疲劳数据来对老化的发电装置进行寿命评估。     

Meta‐Regression Methods for Detecting and Estimating Empirical Effects in the Presence of Publication Selection*

This study investigates the small‐sample performance of meta‐regression methods for detecting and estimating genuine empirical effects in research literatures tainted by publication selection. Publication selection exists when editors, reviewers or researchers have a preference for statistically significant results. Meta‐regression methods are found to be robust against publication selection. Even if a literature is dominated by large and unknown misspecification biases, precision‐effect testing and joint precision‐effect and meta‐significance testing can provide viable strategies for detecting genuine empirical effects. Publication biases are greatly reduced by combining two biased estimates, the estimated meta‐regression coefficient on precision (1/Se) and the unadjusted‐average effect.     

Estimating the Precision of Information on Earnings and Non-earnings Announcement Days,and Its Relation with the Cost of Equity

ABSTRACT

Using daily stock returns, we estimate the precision of information during earnings and non-earnings announcement days, and find that although the precision of information in daily stock returns increases during earnings announcement days, it explains less of the variation in expected returns than the precision of information on non-earnings announcement days. Our findings suggest that the precision of earnings disclosures has a small effect on the cost of equity relative to the precision of information on other days of the year.     

A simple and efficient method for estimating the magnitude and precision of welfare changes: comment

A recent article (Breslaw and Smith, 1995 ) published in this journal provided an iterative numerical technique for computing the welfare effects of price changes. In this note we take issue with the application used to demonstrate this technique. In particular, we show that the demands used are inappropriate and that the authors incorrectly interpret the precision of the estimates of welfare change. Copyright © 2002 John Wiley & Sons, Ltd.     

GPS水准精度评定方法分析

GPS技术的发展,特别是厘米级似大地水准面的发展,为GPS测量正常高提供了技术基础,然而把GPS测量大地高转换成正常高仍存在多种方法的优选问题。本文就GPS测量大地高转换成水准高的精度问题进行分析,给出了精度评定的具体方法,并提出四项提高GPS水准精度的具体措施。     

影响压气机转子叶片精锻质量的主要工艺分析

飞机发动机的压气机转子叶片形状复杂,精度要求高,精密锻造是目前此类叶片叶身加工最为有效的工艺方法。但这类叶片精密锻造工艺流程长,要获得高质量的精密锻件难度不小。下料、挤压、预锻、终锻、切边等几个工序是影响钛合金叶片精锻质量的主要工序,这些主要工序在叶片精锻过程中容易出现哪些质量问题,是文章重点关注的内容并提出了相应的解决措施。     

Establishing a reputation for dependability by means of inflation targets

This paper develops a simple intertemporal model of inflation targets within a framework in which the public is uncertain about the dependability of policymakers, and in which policymakers do not perfectly control inflation. The framework is used to evaluate the effects of various parameters like the rate of time preference, initial reputation, and transparency (or precision of inflation control) on planned inflation, announced targets and the evolution of reputation and of inflationary expectations. The paper also shows that, when allowed to choose the precision of inflation control, more dependable policymakers will often choose relatively more precise control procedures. Implications for the type of inflation stabilization (cold turkey or gradual) chosen by dependable policymakers are also derived. Received: February 15, 1999 / Accepted: March 26, 1999     

盾构机姿态参数测量技术研究

根据三点决定一个平面的原理,通过在盾构机中体上布置测量控制点,对其三维坐标进行测量;根据空间解析几何原理,推导出盾构机刀盘中心三维坐标以及俯仰角、横摆角、扭转角的计算方法。文章利用计算机的伪随机函数对盾构机姿态参数的测量精度进行了模拟评价,探讨了提高测量精度的方法。结果表明,盾构姿态参数的测量误差均服从正态分析;采用精度为3mm的激光经纬仪测量控制点坐标,得到的盾构姿态参数的误差范围比规范要求小得多。     

精密装备制造企业科技管理模式的研究

精密装备制造业是为国防和经济提供生产、技术装备的制造业,能够提供广义制造业所需的关键设备及零部件,处于制造产业链的顶端,是制造业的核心组成部分,涉及极多的复杂、精密和尖端技术。论文首先概述了精密装备制造企业的特征及现状,并基于传统精密装备制造企业科技管理模式的问题,分别从以持续眼光优化项目、处理技术创新与技术引进的关系、重视并加强风险管控和产学研等方面,就精密装备制造企业科技管理模式的优化提出了建议。     

News,disaster risk,and time-varying uncertainty

Standard real business cycle models are often unable to replicate three empirical facts: positive output in response to good news, stochastic volatility of macro variables, and asymmetric business cycles. This paper proposes a unified basis for understanding these facts in a tractable dynamic stochastic general equilibrium (DSGE) model, in which the key is the interaction of information flows and disaster risk. Information flows fluctuate between two regimes with different precision levels for signals regarding future economic fundamentals. A shift in forecast precision changes the probability of entering an economic disaster. High disaster risk leads to low expected capital returns and a decline in hours, investment, and output. Changing information structures results in different volatility and skewness over the business cycle. Simple theory makes the two expectation effects through information flows and disaster risk transparent. Quantitatively, the model suggests that the interaction of the two expectation effects plays a significant role in accounting for the higher-order moments of the business cycle.     

量块定位方式对坐标测量机精度的影响

量块的定位方式对校准坐标测量机的尺寸测量参数有着重要影响。本文首先分析了标准量块的两种定位方式对校准精度的影响。在实际校准工作中,以不同尺寸的标准量块采取不同的定位方式来减少定位误差提高校准精度,并进行不确定度分析。