短期负荷预测中考虑积温效应的温度修正模型研究

由于夏季负荷受温度因素影响较大,持续高温天气会造成积温效应,导致负荷出现一定程度的非常规增长,传统的短期负荷预测方法难以满足实际需求。因此,为了反映积温效应的影响程度,本文提出了温度修正模型,通过拟合温升曲线、求解负荷温度弹性系数来确定高温日的界限温度,同时给出了利用相关系数求解最大累计天数和累积效应系数的方法。算例分析表明,所提出的方法能够准确地反映积温效应的影响,提高短期负荷预测的精度。     

宁夏夏季日数相关要素的变化特征及其对气候变暖的响应

采用1961—2010年宁夏逐日最高气温资料,分区域分析了夏季日数相关要素的变化特征及其对气候变暖的响应.结果表明,各区域夏季日数均有上升趋势,于1997—1998年发生突变,夏季日数上升速率为2.6~3.9 d/10 a,其中引黄灌区最大;日最高气温〉25℃的起始和终止日期分别有提前和推迟趋势,起始日期提前增加了春季发生霜冻的风险性,引黄灌区和南部山区分别有以起始日期显著提前和终止日期明显推迟为特征的延长趋势;中北部地区夏季日数的极端性趋势显著.各要素对气候变暖有不同程度的响应,响应趋势及显著性与各要素变化趋势基本一致;年平均气温每增加1℃,夏季日数增加9.5~11.1 d,南部山区增加最多;日最高气温〉25℃的终止日期对气候变暖最为敏感,其他要素突变时间均滞后于年平均气温的突变时间.     

数据挖掘与非正常日的负荷预测

提高非正常日的负荷预测精度是当前负荷预测工作的难点。文中提出了一种基于知识库的事先判别突变并做出适当处理的预测流程,介绍了利用数据挖掘的决策树技术建立知识库的方法,并给出了几种典型的非正常日修正模型。最后,通过对长时期负荷预测数据的统计分析,说明了新方法的有效性和实用性。     

电网负荷采用最大3d平均负荷指标的探讨

分析了采用最大3d平均负荷指标对电网运行的经济性和必要性.随着国内电力供需矛盾趋缓,采用最大3d平均负荷作为电网最大负荷的时机已趋成熟,应参照日本等国的经验,尽早采纳该方法.     

典型气象因素对省网夏季日最大负荷的影响

针对湖南省的气象特点和电源特点,研究该地区夏季持续高温、连续晴天和持续降水等典型气象因素对省网日最大统调负荷的影响．刻画高温累积效应以直观描述持续高温对负荷产生的影响,定义连续晴天数和降水累积滞后效应,用以反映连续晴天和持续降水对小水电出力的影响．通过分析典型气象因素和人们生产生活规律等影响因素,建立基于差分法的多元线性短期负荷预测模型．对近年湖南夏季日最大统调负荷进行模型仿真和实例预测,取得了较好的预测效果．     

Selection of typical demand days for CHP optimization

Optimizing the configuration and operation of a CHP system for a whole year becomes a computationally demanding task when, for example, integer variables are used to model the status (on/off) of different pieces of equipment. The reason is that a discrete optimization problem is fundamentally an enumerative problem, featuring that the number of possible solutions grows exponentially with the number of integer variables. This computational difficulty is known as the curse of dimensionality, and severely limits the chances to use mixed integer programming methods to design CHP systems. To work out this problem, this paper presents a new and unambiguous method to reduce a full year of demand data to a few representative days that adequately preserve significant characteristics such as the peak demands, the demand duration curves, and the temporal inter-relationship between the different types of demands (power, heating, and cooling). Days are selected using a partitional clustering method known as the k-medoids method, and their ability to resemble the original data is tested by means of two quality indexes and a calendar visual inspection. Two case studies are discussed for the completeness of the paper, showing how the method and the quality indexes can be used in practice.     

Latitudinal gradient of floristic condition among Great Lakes coastal wetlands

Coastal wetland vegetation along the Great Lakes differs strongly with latitude, but most studies of Great Lakes wetland condition have attempted to exclude the effect of latitude to discern anthropogenic effects on condition. We developed an alternative approach that takes advantage of the strong relationship between latitude and coastal wetland floristic condition. Latitude was significantly correlated with 13 of 37 environmental variables tested, including growing degree days, agriculture, atmospheric deposition, nonpoint-source pollution, and soil texture, which suggests that latitude is a good proxy for several environmental drivers of vegetation. Using data from 64 wetlands along the U.S. coast of Lakes Huron, Michigan, Erie, and Ontario, we developed linear regressions between latitude and two measures of floristic condition, the Floristic Quality Index (FQI, adj. r² = 0.437, p < 0.001) and the first axis scores from a non-metric multidimensional scaling of wetland plant cover (MDS1, adj. r² = 0.501, p < 0.001). Departures from the central tendency of these regression models represented wetlands of better or worse condition than expected for their latitude. This approach provides a means to identify wetlands worthy of preservation, to establish vegetation targets for wetland restoration, and to forecast changes in floristic quality associated with future climate change.     

五日生化需氧量(BOD_5)测定时防止氨氮干扰的方法探讨

生化处理后的水样富含硝化细菌,当氨氮含量较高时会对五日生化需氧量(BOD5)的测定产生干扰。该文对硝化抑制剂的加入做了对比研究,旨在找出适合再生水BOD5测定的方法。     

大兴安岭雷暴日数的时空分布特征

利用大兴安岭地区1980--2008年的雷暴观测资料,对大兴安岭地区雷暴天气的时空分布特征及初、终雷目的变化特征等进行了分析,结果表明：大兴安岭地区年雷暴日数的分布与测站地理位置及纬度有关,近年来年平均雷暴日数以加格达奇为最多,呼玛为最少;年平均雷暴日数的多少与雷暴期的长短无关。大兴安岭地区的雷暴表现出明显的季节性特征,即雷暴多生在夏季,春秋季次之,冬季没有雷暴产生,7月份为雷暴出现的高峰月。雷暴的初、终日出现日期与候平均气温有关。     

浅谈特殊气候条件下水泥混凝土路面施工

详细介绍了水泥混凝土路面在高温季节、低温季节和雨季三种特殊气候下的施工工艺,从一般规定、施工要求及对特殊环境的特殊要求三方面进行了具体阐述,以指导实践。