基于SBM-GWR模型的中国省际用水效率及其影响因素分析

针对目前用水效率相关研究中较少考虑用水产生的社会效益的不足,基于2003～2017年的面板数据和SBM-DEA模型,将社会发展指数纳入期望产出评估中国30个省市的用水效率;采用Tobit模型和地理加权回归模型,定量分析我国各省域用水效率的影响因素及其时空分布特征。结果表明,我国27个省市用水未能达到有效状态,存在投入冗余或产出不足现象;各影响因素对用水效率的影响具有时空差异性;不同影响因素对各省用水效率的影响程度存在差异,其中受教育年限影响程度最高。     

农村配电网技术线损评估模型研究

针对我国农村配电网的特殊情况,传统电网分析方法难以适用,同时一般的技术线损计算方法存在精度低或计算量大的问题,在应用人工智能的过程中,忽视了技术线损这一影响因子。所以,我们在研究农村配电网技术的过程中,要及时、快速、精准地了解技术线损原因,是当前需要重点解决的课题。为了更好地攻克这些难题,笔者通过模型分析法研究农村配电网技术线损,建立其特征分析及评估模型。所谓特征分析模型,主要是分析选择影响配电网技术线损的特征,而特征评估模型则用于验证所选线损特征的有效性。     

基于“EGM-PCA”组合算法的县域配电网评估模型构建

传统配电网评估模型对配电网评估目标的划分不细致,导致评估准确率低。针对这一问题,设计了基于“EGM-PCA”组合算法的县域配电网评估模型。利用主成分分析法将复杂配电网目标问题分解为多个目标,进而将目标分解成若干个小目标。通过判断矩阵对目标进行权化分析并进行排序。根据排序结果,利用递归运算对县域配电网目标进行权重计算。根据权重计算结果设计了具有安全性、技术性、可靠性与经济性的县域配电网评估指标,利用评估指标构建县域配电网评估模型。实验结果表明,基于“EGM-PCA”组合算法构建的县域配电网评估模型对于配电网目标的划分较为细致,评估准确率高,具有很好的发展前景。     

基于GWR的区域年太阳辐照量计算模型

将地理加权回归分析(GWR)应用于区域年太阳辐照量计算,在GIS技术支持下,利用194个气象观测基本站逐月观测数据,以年平均气温、年日照时数、年平均总云量以及海拔高程作为影响因子,以地理加权回归分析作为计算方法,建立基于GWR模型的区域年太阳辐照量计算模型。对比利用模型计算的区域年太阳辐照总量与同一地区观测的年太阳辐照总量,拟合值与观测值之间的误差最大为9.65%,最小误差为0.02%,表明基于GWR模型建立的区域年太阳辐照量计算模型具有较好的计算精度。     

复合抛物面太阳能集热器热性能分析

对真空管式复合抛物面太阳能集热器的传热模型进行了分析,在总热损失系数、效率因子、热迁移因子和瞬时效率表达式的基础上,建立了有盖板带翅片的复合抛物面集热器性能预测模型,并对有盖板和无盖板两种类型接收器的集热器进行了瞬时效率的对比计算.结果表明：当集热介质与外界环境间温差较小时,在相同辐射强度的情况下,有盖板带翅片的复合抛物面集热器的集热效率反而比无盖板的复合抛物面集热器的集热效率低;而当集热介质与外界环境温差增加到一定程度时,有盖板带翅片的复合抛物面集热器显示了其集热效率高的优点.     

基于最小路的配电网可靠性评估开关简化模型

为分析复杂配电网的可靠性,提出了一种基于最小路的可靠性评估开关简化模型。依据配电网安装大量开关的特点,以开关为核心,建立了配电网可靠性评估的开关简化模型,并依据图论理论最小路的概念与算法,结合配电网运行呈现辐射状的特点,将最小路搜索算法与配电网可靠性评估的开关简化模型相结合,提出了一种新的配电网可靠性计算方法,以算例计算验证了该方法的有效性。     

随机源-荷影响下配电网运行不确定性量化理论方法与应用展望

分布式可再生能源和新型再电气化负荷接入配电网促进了能源的低碳化生产与消费,也引入了大量的源-荷不确定性因素,给配电网的安全运行带来了挑战。为量化评估随机源-荷的影响,从配电网源-荷不确定性因素建模出发,提出了涵盖不确定性表征和灵敏度分析的配电网运行不确定性量化理论框架。在不确定性表征方面,从计算效率和准确性出发,总结了现有基于高保真度模型和低保真度模型的不确定性表征方法,并提出了基于多保真度模型的不确定性表征方法;在灵敏度分析方面,引入了基于方差、面积和距离的全局灵敏度分析方法,并对比了不同灵敏度分析方法的特点与适用场景。通过展望所提不确定性量化理论在耦合系统中的应用,以期为多时间尺度运行下耦合系统的不确定性分析研究提供方法支撑。     

低压配电网对电动汽车充电的承载能力

规模化电动汽车的接入将会对配电网的运行与规划产生不可忽视的影响,合理评估配电网对电动汽车充电负荷的承载能力有利于消除电动汽车充电负荷对于配电网的不利影响.基于最常见的辐射型配电网模型,采用数学解析的方法建立了低压配电网对电动汽车充电负荷承载能力的分析模型.全面揭示了低压配电网对电动汽车充电负荷承载能力的各影响因素及其变...     

降水分布指数模型精度分析及验证

为评估降水分布指数模型(DPEM)的精度问题,基于圣卡塔利娜岛4场次降雨7个观测站点的实测数据,分别运用距离倒数加权插值模型(IDW)、修正距离倒数插值模型(RIDM)、空间线性插值模型(SLIM),通过交叉验证,比较了四种模型的插值精度。结果表明,对不同验证站进行插值时,各方法呈现不同特征。验证站位于样本地理分布边缘时,SLIM、IDW模拟误差有增大趋势;RIDM考虑高程作为权重因子后,模拟结果优于IDW;而DPEM模拟产生的误差更小,且能够反映降水中心的趋势位置。该评估比较对降水分布指数模型在降水数据输入时有指导意义。     

考虑能控能观性的配电二次设备优化配置模型与评估方法

新型电力系统背景下,配电网控制与观测难度显著提升。然而,现有的配电网能控能观性研究以及相应的配电二次设备规划模型难以满足配电网实际控制与观测的需要。为此,提出了基于能控能观分析的配电二次设备优化配置模型与评估方法。首先,提出了配电网能控能观性及相关指标的完整数学定义。其次,构建了能控能观需求-状态变量的映射集合。最后,提出了配电二次设备的优化规划模型及多维评估方法。算例分析表明,所提规划模型及评估方法以最小的经济成本实现了综合效益的最大化,具备可行性与有效性。     

Quality frontier of electricity distribution: Supply security,best practices,and underground cabling in Finland

Electricity distribution is a prime example of local monopoly. In most countries, the costs of electricity distribution operators are regulated by the government. However, the cost regulation may create adverse incentives to compromise the quality of service. To avoid this, cost regulation is often amended with quality incentives. This study applies theory and methods of productivity analysis to model the frontier of service quality. A semi-nonparametric estimation method is developed, which does not assume any particular functional form for the quality frontier, but can accommodate stochastic noise and heteroscedasticity. The empirical part of our paper examines how underground cabling and location affect the interruption costs. As expected, higher proportion of underground cabling decreases the level of interruption costs. The effects of cabling and location on the variance of performance are also considered. Especially the location is found to be a significant source of heteroscedasticity in the interruption costs. Finally, the proposed quality frontier benchmark is compared to the current practice of Finnish regulation system. The proposed quality frontier is found to provide more meaningful and stable basis for setting quality targets than the average practice benchmarks currently in use.     

Estimating an economic-efficient frontier for dishwasher consumer choice

Dishwashers are a ubiquitous appliance in households in the USA. They combine capital, energy, and water to provide a relevant household service, namely dishwashing. The economic efficiency of dishwashers has been previously assessed using data envelopment analysis (DEA). The approach addresses the technical efficiency of dishwashers based on possible trade-offs between capital and energy. It further draws from the technical efficiency scores an efficient frontier for dishwashing based on these two input factors. We argue that water could also be a relevant input factor to that frontier, especially from the perspective of consumer choice. We develop a DEA model that includes water as an additional input and test if adding water to the analysis contributes to the efficiency frontier. We find that water does have some effect on the frontier, as the DEA model that includes water as an input factor leads to a richer set of efficient possibilities for dishwashing, where energy and water are traded off. We rely on our method and findings to propose two approaches to inform dishwasher consumer choice. One is extending an energy label to include dishwasher water consumption, as a means to inform consumers on their possible trade-offs between energy and water consumption at different levels of appliance price and quality. The other one is disclosing the DEA efficiency scores we estimate as an indicator of the overall economic efficiency of each dishwasher model.     

Manufacturing productivity and energy efficiency: a stochastic efficiency frontier analysis

This paper presents a mathematical model to estimate both production frontier and energy demand frontier, and evaluate the energy efficiency in the automotive manufacturing sector using plant‐level production and utility consumption data. By using the stochastic frontier analysis, two models—an output efficiency model (production frontier) and an input efficiency model (energy demand frontier)—are developed to analyze the plant's energy efficiency performance relative to the ‘best practice’ among peers. Both the structure and parameters of two stochastic frontier functions are identified to understand the relationship between production inputs (e.g., utilities and plant‐specific variables) and the overall productivity. A case study of a set of automotive engine manufacturing plants is conducted and shows that electricity has higher efficiency than other forms of utility in those production‐related activities, and the regional and climate factors have significant impacts on energy efficiency. The models provide a way to measure how far from the production frontier as well as how far from the energy demand frontier the plant is. The results also provide useful information about the inefficient energy components in manufacturing facilities. The opportunities of improving plant‐level efficiency in automotive manufacturing plants can be revealed by the results. Copyright © 2015 John Wiley & Sons, Ltd.     

The exogenous factors affecting the cost efficiency of power generation

This paper employs a stochastic frontier analysis (SFA) to examine cost efficiency and scale economies in Taiwan Power Company (TPC) by using the panel data covering the period of 1995–2006. In most previous studies, the efficiency estimated by the Panel Data without testing the endogeneity may bring about a biased estimator resulting from the correlation between input and individual effect. A Hausman test is conducted in this paper to examine the endogeneity of input variables and thus an appropriate model is selected based on the test result. This study finds that the power generation executes an increasing return to scale across all the power plants based on the pooled data. We also use installed capacity, service years of the power plant, and type of fuel as explanatory variable for accounting for the estimated cost efficiency of each plant by a logistic regression model to examine the factor affecting the individual efficiency estimates. The results demonstrate that the variable of installed capacity keeps a positive relationship with cost efficiency while the factor of working years has a negative relationship.     

Effects of substituting energy with capital on China's aggregated energy and environmental efficiency

Substituting energy with capital (SEC) in economic productions has become a common practice both for business owners and policy-makers to improve their energy and environmental efficiency. However, seldom previous studies on energy efficiency and/or environmental performance evaluation took this role into account. This paper aims to shed some light on the effects of SEC on China's aggregated energy and environmental efficiency (AEEE) within a parametric stochastic frontier analysis framework. Moreover, influencing factors of regional efficiency score are also discussed using a pooled regression model. The results indicate that SEC poses significant effects on improving China's AEEE, and this impact appears obvious regional variation that regions with lower efficiency scores hold more extensive potential to improve their AEEE by means of SEC. Furthermore, upgrading industrial structure and decreasing the proportion of coal in energy consumption make great sense to improve China's AEEE.     

Does environmental heterogeneity affect the productive efficiency of grid utilities in China?

China's electric power industry has experienced a reform whereby the generation sector is being opened up to competition but the transmission and distribution sectors are still under regulation. Efficiency and benchmarking analyses are widely used for improving the performance of regulated segments. The impact of observable environmental factors, together with unobservable characteristics, on efficiency has gained increasing attention in recent years. This study uses alternative stochastic frontier models combined with input distance functions to measure the productive efficiency of 29 grid firms of China over the period of 1993–2014 and investigates whether the observed environmental and unobserved heterogeneity factors affect the productive efficiency. The results indicate that adverse environmental conditions may bring negative influence to the production of grid utilities while the number of customers and the network length have positive impacts on the utilities' efficiency; Besides, the efficiency is sensitive to the model specification, which illustrates the presence of observed and unobserved heterogeneity; Moreover, there is no significant efficiency improvement in the grid utilities after the unbundling reform of 2002; Finally, the regional grids differ significantly in efficiency, and there is room for improvement, which could be achieved by incentive regulation taking due account of environmental heterogeneity.     

Spatial statistical methods applied to the 2015 Brazilian energy distribution benchmarking model: Accounting for unobserved determinants of inefficiencies

In 2015 the Brazilian regulator presented a DEA benchmarking model to set the regulatory operational cost goals, to be reached in four years for 61 electricity distribution utilities. The DEA model uses: adjusted operational cost as the input variable, seven output variables and weight restrictions. Although non-discretionary variables or environmental variables are available in the dataset, the regulator argued that no statistically significant correlation was found between the DEA efficiency scores and the non-discretionary variables. This study evaluates the statistical correlation between the DEA efficiency scores and the available environmental variables. Spatial statistic methods are used to show that the efficiency scores are geographically correlated. Furthermore, due to Brazil's environmental diversity and large territory it is unlikely that only one environmental component is sufficient to adjust inefficiencies across the Brazilian territory. Thus, a new combined environmental variable is proposed. Finally, a second stage model using the proposed environmental variable and accounting for a spatial latent structure is presented. Results show major differences between original and corrected efficiency scores, mainly for utilities located in harsh environments and which originally achieved lower efficiency scores.     

An efficiency analysis of household energy use

A new method to estimate the energy efficiency of households is presented. Households are treated as productive units organized to provide services for the occupants. The approach to measuring efficiency compares a group of productive units along several dimensions of input resources and service outputs. The comparison identifies a subset of units that are considered efficient because they require the fewest resources per unit of service provided. The efficient units form a production possibility frontier of best practice in service provision. All other units are compared to this best practice frontier and their index of efficiency is based on their distance from that frontier. Data from the 1979 Household Screener Survey are used to construct a household typology. Two different energy efficiency models are explored. One model uses the annual consumption of electric and non-electric fuels as the input resources. The other uses the annual expenditures for the two fuel types. Both models use the number of rooms and the number of people in the dwelling as proxies for the service outputs. A regression analysis of the two sets of efficiency scores indicates that the more efficient units used electric heat, had higher ratios of non-electric to electric fuel inputs, and were owner-occupied.     

A new long term load management model for asset governance of electrical distribution systems

Long term load management (LTLM) is one of the key factors in making decisions regarding new investments in distribution systems. However, none of the previous studies have investigated the effect of external factors such as governance, urban planning and social behavior factors on LTLM. In this paper, a new LTLM model is proposed to determine the influence of external factors on LTLM. Distribution system development indices have been used to obtain asset governance targets; these indices can help Distribution Companies (DISCOs) compromise between reliability and running the system economically. Capacity utilization and the number of maneuver points are used here to do LTLM and improve asset governance. Numerical studies on a real distribution system (city with population about 200,000) have been conducted and sensitivity analysis of maneuver points and capacity utilization level with respect to external factors is studied and analyzed. The results show the feasibility of the proposed LTLM to obtain higher efficiency from the viewpoint of cost and quality service compared to conventional LTLM.     

Heterogeneous technologies,strategic groups and environmental efficiency technology gaps for European countries

This paper measures technology (TG) and environmental efficiency technology gaps (EETGs) in 25 European countries over two distinct periods 2002 and 2008 examining the possible effect of adopted environmental regulations and the Kyoto protocol commitments on environmental efficiency technology gaps. However, the introduction of the metafrontier in our analysis puts into our discussion the role of heterogeneous technologies and its effect on the above-mentioned measures. Employing a directional distance function, we investigate whether there is an actual difference, in terms of environmental efficiency and efficiency performance, among European countries considering the technological frontiers under which they operate. The construction of individual frontiers has been realized employing a large number of variables that are highly correlated with countries' learning and absorbing capacity, new technological knowledge and using economic theory and classical frontier discrimination like developed vs. developing, North vs. South and participation in the Eurozone or not. The overall results indicate a crucial role of heterogeneous technologies for technology gaps in both periods. Moreover, a significant decrease for both measures, although in different percent, has been recorded emphasizing the key role of knowledge spillovers.