Efficiency Of Distribution System Research Articles

A Study of Energy Optimisation of Urban Water Distribution Systems Using Potential Elements

Energy use in water supply systems represents a significant portion of the global energy consumption. The electricity consumption due to the water pumping represents the highest proportion of the energy costs in these systems. This paper presents several comparative studies of energy efficiency in water distribution systems considering distinct configurations of the networks and also considers implementation of the variable-speed pumps. The main objective of this study is the energy optimisation of urban systems using optimal network configurations that reduce energy consumption and improve energy efficiency. The paper describes in detail four strategies for improving energy efficiency of water pumping: control systems to vary pump speed drive according to water demand, pumped storage tanks, intermediary pumping stations integrated in the network, and elevated storage tanks floating on the system. The improving energy efficiency of water pumping is briefly reviewed providing a representative real case study. In addition, a different approach for the hydraulic analysis of the networks and the determination of the optimal location of a pumped storage tank is provided. Finally, this study compares the results of the application of four water supply strategies to a real case in Romania. The results indicate high potential operating costs savings.

Assessing Location and Scale of Urban Nonpotable Water Reuse Systems for Life-Cycle Energy Consumption and Greenhouse Gas Emissions.

Nonpotable water reuse (NPR) is one option for conserving valuable freshwater resources. Decentralization can improve distribution system efficiency by locating treatment closer to the consumer; however, small treatment systems may have higher unit energy and greenhouse-gas (GHG) emissions. This research explored the trade-off between residential NPR systems using a life-cycle approach to analyze the energy use and GHG emissions. Decentralized and centralized NPR options are compared to identify where decentralized systems achieve environmental advantages over centralized reuse alternatives, and vice versa, over a range of scales and spatial and demographic conditions. For high-elevation areas far from the centralized treatment plant, decentralized NPR could lower energy use by 29% and GHG emissions by 28%, but in low-elevation areas close to the centralized treatment plant, decentralized reuse could be higher by up to 85% (energy) and 49% (GHG emissions) for the scales assessed (20-2000 m3/day). Direct GHG emissions from the treatment processes were found to be highly uncertain and variable and were not included in the analysis. The framework presented can be used as a planning support tool to reveal the environmental impacts of integrating decentralized NPR with existing centralized wastewater infrastructure and can be adapted to evaluate different treatment technology scales for reuse.

Pollution impact of residential loads on distribution system and prospects of DC distribution

Unlike in the previous decades, the recent past saw the advent of many modern appliances in residential buildings. The unique feature in most of these appliances is that they use direct current (dc) in their internal circuits. With an already established alternating current (ac) distribution system in the present scenario, this situation calls for an in-depth analysis for a suitable dc distribution scheme to improve power quality and efficiency. In this paper an extensive survey of loads is conducted in various residential buildings supplied by different distribution transformers and their harmonic pollution impact on the system is investigated. To improve the efficiency and power quality of the traditional domestic distribution system, a dc distribution scheme is proposed which reduces harmonics and neutral loading of distribution transformers. The scheme can be made effective by shifting the harmonic inducing loads to the dc network side. This system also eliminates redundant power conversion stages involved in the integration of renewable energy sources in the conventional distribution system. The effectiveness of the system is validated by simulating a prototype distribution system and the results are verified experimentally.

Use C‐Factor Testing to Improve Water Distribution Systems

Smooth pipe walls ensure maximum flow capacity for water transmission and distribution. C‐factor testing is an effective, noninvasive way to determine distribution system efficiency.

파티션 시스템 적용을 통한 기존 데이터센터 서버실의 냉방 에너지 절감 성능평가

본 연구에서는 기존 데이터센터 서버실에서 공기분배시스템으로 파티션 시스템의 적용성을 평가하기 위해 기존 시스템 그리고 파티션의 설치 높이와 위치를 변수로 하는 파티션 시스템과 컨테인먼트 시스템에 대해 총 21가지 경우의 컴퓨터시뮬레이션을 실시하고 다음과 같은 결론을 얻었다. 공기온도 및 기류 분포 해석결과를 이용하여 평가해 본 공기분배시스템별 냉방 에너지 절감 성능은 컨테인먼트 시스템, 파티션 시스템, 기존 시스템 순서로 우수한 것을 확인할 수 있었다. 기존 시스템과 파티션 설치높이 0.1~0.7m까지의 파티션 시스템은 재순환 공기에 의해 냉복도에서 1.0~1.2m 높이를 기점으로 공기 온도가 급격히 상승하면서 중간 높이의 서버와 상부 서버의 인입구 온도차는 <TEX>$11{\sim}15^{\circ}C$</TEX>로 큰 차이를 보여, 재순환 공기가 상부 서버의 과열의 원인을 제공하는 것으로 나타났다. 파티션 시스템에서 냉복도 상부에 파티션을 설치할 경우에 파티션의 적정 높이는 서버 랙 상부에서 천장까지 높이의 90%(0.9m)이상, 열복도 상부에 파티션을 설치하는 경우는 파티션 높이가 80%(0.8m)이상은 되어야 재순환 공기를 충분히 차단하여 서버 인입구 공기온도가 RCI 권장온도 범위를 만족하는 냉방 에너지 절감효과를 볼 수 있는 것으로 나타났다. In this study, a computer simulation of the three types of air distribution systems, open type system, aisle partition system and aisle containment system, to evaluate the applicability of the aisle partition system on a data center server room. The variables of the simulation were the height and location of the partition fixed on the top server rack. The energy efficiency of the air distribution systems were confirmed to be excellent in the order of the aisle containment system, aisle partition system, and open type system. In the cold aisle partition system, the height of the partition that can be effective in saving cooling energy by obstructing sufficient air recirculation was found to be more than 0.9m. In the hot aisle partition system, the height of the partition was found to be more than 0.8m.

Investigations on the Energy Efficiency of Stratified Air Distribution Systems with Different Diffuser Layouts

This paper investigated the influence of diffuser layouts on the energy performance of stratified air distribution systems (STRAD). The energy saving potentials of STRAD systems are theoretically analyzed. The cooling coil load of a STRAD system is proportion to the return air temperature, while inversely proportional to the exhaust air temperature. Based on that, numerical studies are conducted for the applications of STRAD systems in three typical building space types. Two evaluation indices are developed to assess the energy performance of STRAD systems. The simulation results demonstrated that further energy saving could be achieved by keeping the exhaust grille at ceiling level and decreasing the height of return grille. Therefore, in order to optimize the energy saving capacity of STRAD systems, the return grille is recommended to be located as low as possible, whilst paying special attention on the “short-circuit” of cold supply air. Furthermore, when the STRAD system is applied in large space buildings with a big horizontal span, supply diffusers should be distributed surrounding the occupied zone as uniformly as possible, while avoiding installing return diffusers at exterior walls.

Remote Data Monitoring Improves Distribution System Efficiency and Maintenance

Water and wastewater utilities are drawing on advances in distribution monitoring technologies to improve their distribution systems. Today's remote data monitoring tools efficiently and accurately collect pressure and other data, enabling faster response times.

Single Tuned Harmonic Shunt Passive Filter Design for Suppressing Dominant Odd Order Harmonics in order to Improve Energy Efficiency

Power quality refers to the provision of the clean and stable electrical power supplies with least interruptions of current and voltage However, power quality problems arise due to the application of nonlinear loads with end user devices. Electrical installations majorly suffer from adverse effects of harmonic currents and voltages. Though, this problem has been decades long and pattern of investigation for the researchers but due to evolution of semiconductor technology, it has become burning issue with reference to the power system loads. Therefore, it becomes necessary to mitigate these harmonics for the safe operation of electrical appliances. Thus, harmonic passive filters are cost effective and easy to implement. In this work, the mitigation of current harmonics has been accomplished through single tuned Shunt Harmonic Passive Filter (SHPF). Furthermore, the application of six pulse multiplication converter technique ensures the mitigation of dominant 3rd harmonic currents and reduction of succeeding 5th and 7th harmonic currents. Furthermore, shunt operation of single tuned harmonic passive filter enables the current to follow the low impedance path. Consequently, the current harmonic distortion becomes less than 5 % according to allowable IEEE 519 -1992 standards. This reduction in harmonic distortion not only reduces the losses incurred in the system but it also improves the energy efficiency of the electrical Power Distribution System (PDS).

Smart City Wireless Connectivity Considerations and Cost Analysis: Lessons Learnt From Smart Water Case Studies

According to estimates from the United Nations, while the world population is likely to reach 9 billion by 2050 (from around 7 billion today), the water resources available to cater to this population are likely to remain similar to what they are today. Therefore, there is a growing concern to reduce water wastage and improve the efficiency of water distribution systems, in particular, urban water systems given the proliferation in both the number of cities that are springing up and the number of people moving to live in cities. Motivated by this, the European Commission under the aegis of the Framework Program (FP7) funded the Information and Communications Technology (ICT) Solutions for the Efficient Water Resources Management project. This Smart Water project is aimed at investigating the role of ICT in monitoring and efficiently managing urban water systems, in particular, exploring the deployment of sensors, communication technologies, and associated decision support systems in utility providers water networks geared toward addressing problems, such as leakage management, demand management, asset management, and so on. This article elaborates on the wireless connectivity considerations, proposes a total cost of ownership framework for evaluating candidate solutions, and highlights experiences from Smart Water case studies involving two utilities in Europe.

Implementation of multi-objective seeker-optimization-algorithm for optimal planning of primary distribution systems including DSTATCOM

Abstract This paper develops an approach based on a multi-objective seeker-optimization-algorithm (MOSOA) for designing of an advanced power distribution system (PDS) including distribution static compensator (DSTATCOM). The proposed planning methodology uses a contingency-load-loss index (CLLI) for reliability evaluation, which is independent of the failure rate and fault repair duration of the feeder branches, which is difficult to obtain in practice. To enhance the reliability and operation efficiency of the conventional power distribution system, the proposed approach includes distribution automation devices such as automatic reclosers (RAs) in the planning strategy. The proposed study simultaneously obtains the optimal placement and sizing of the DSTATCOM in reactive power compensation for system voltage control to avoid the voltage violation problem. The effectiveness of the proposed algorithm is tested on a 54-bus distribution system, considering real-time design practices. The information gained from the pareto-optimal solution is shown to be useful for final decision making of a PDS. Furthermore, a qualitative comparison is made with NSGA-II, showing the efficiency of the proposed planning approach. The presented results show the accuracy and efficiency of the proposed method.

Technologies used in Smart Grid to implement Power Distribution System

&lt;span style="line-height: 107%; font-family: 'Arial',sans-serif; font-size: 9pt; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US"&gt;Recently, the debate has been going on about the role of power plus distribution systems, its technologies for future smart grids in power systems. The emerging of new technologies in smart grid and power distribution systems provide a significant change in terms of reduction the commercial and technical losses, improve the rationalization of electricity tariff. The new technologies in smart grid systems have different capabilities to increase the technological efficiency in power distribution systems. These new technologies are the foreseeable solution to address the power system issues. This paper gives a brief detail of new technologies in smart grid systems for its power distribution systems, benefits and recent challenges. The paper provides a brief detail for new researchers and engineers about new technologies in smart grid systems and how to change traditional distribution systems into new smart systems.&lt;/span&gt;

Investigation on the thermal comfort and energy efficiency of stratified air distribution systems

A stratified air distribution (STRAD) system is a feasible air conditioning design for large space buildings that satisfies the energy conservation and thermal comfort requirements. In this paper, a novel energy efficiency index for STRAD systems is developed using theoretical analysis to properly evaluate the system's energy saving potential. Using a validated numerical model, two typical stratified air distribution designs in a hypothetical terminal building are evaluated based on thermal comfort and energy savings. The influence of supply and return diffuser distributions on the ventilation performance of these two ventilation designs is studied. When the air is supplied at mid-height, the local thermal comfort is greatly improved without sacrificing the energy efficiency due to additional return grilles located at exterior walls. When the air is supplied at floor level, installing additional return grilles at exterior walls slightly alleviates the local draft risk, but doing so largely impairs the energy saving capacity of the ventilation system. To achieve better thermal comfort and higher energy efficiency, a more uniform distribution of supply diffusers surrounding the occupied zone is suggested. When the air is supplied at the floor level, increases in solar radiation intensity can be mitigated by utilizing external shading designs, which are particularly important in preventing too large of a temperature gradient in the region exposed directly to the solar radiation.

Spectral efficiency analysis of large‐scale distributed antenna system in a composite correlated Rayleigh fading channel

In this study, the downlink spectral efficiency of multi-cell multi-user large-scale distributed antenna systems (DASs) with pilot contamination is studied in a composite correlated Rayleigh fading channel. Firstly, under a physical channel model, the equivalent channel model of large-scale DAS with pilot contamination is given. Secondly, based on the equivalent channel model, the closed-form expression is derived for the downlink achievable rate with maximum ratio transmission, and the ultimate rate is also given when the ratio of the total number of base station antennas to the number of users goes to infinity. Thirdly, the results are validated via numerical simulations. It is shown that the closed-form expression is very accurate, and the downlink achievable rate of the large-scale DAS is much larger than that of the co-located massive multiple-input multiple-output (MIMO) with the same antenna configuration.

Distribution Network Efficiency Improvement Based on Fuzzy Multi-objective Method

This paper presents a reconfiguration methodology based on a fuzzy multi-objective approach for achieving the minimum active power loss and the maximum voltage magnitude of radial distribution networks with distributed generations in order to improve the distribution system efficiency. Multi-objective function are considered for load balancing among the feeders, minimization of the real power loss, and deviation of bus voltage, while subject to a radial network structure in which all loads must be energized. These objective functions are modeled with fuzzy sets to evaluate the imprecise nature of each objective. Originality of the research is that the fuzzy-based multi-objective optimization in reconfiguration of distribution network including the distributed generation. The implementation of the fuzzy multi-objective for distribution reconfiguration on a 77 bus distribution network with distributed generation is described. The simulation results show that a 1.80% of electric power distribution network efficiency improvement is achieved by the method

SIRKULASI DAN PENGEDARAN MAJALAH MELAYU SEBELUM PERANG DUNIA KEDUA

For a magazine to survive in the market, three elements must be strengthened-the editorial content, circulation or distribution, and income from advertisement. The editorial content is responsible for attracting readers and thus will improve circulation. Increased circulation also often results in increased revenue from advertising. Thus, these three pillars, namely editorial, circulation, and advertising are very important for the survival of a magazine. Circulation refers to the number of copies sold to the readers. A good magazine circulation depends on the efficiency and effectiveness of marketing techniques, as well as the efficiency of distribution system used by the publisher to deliver the magazine to the reader. The publishers of Malay magazines after the Second World War were entirely dependent on circulation of the magazine to cover expenses and to expect profit. This article discusses the circulation and distribution practices of Malay magazines published before the war and its impact on magazines in the market.

English

This paper presents a comprehensive analysis of aggregate technical and commercial losses(AT & C) occur in Power Distribution Sector with special focus on loss reduction and efficiency improvement of power supply. Different major aspects of technical and non-technical losses have been identified and on the basis of that a number of remedial measures have been suggested for loss reduction and to facilitate the improvement of overall efficiency of the power distribution system. The main objective of this paper is to implement a distribution system having negligible Non Technical Losses (NTL).Some case studies (CESC,NDPL) have also been made to reflect the viability of the loss reduction techniques which have been already implemented. This may provide further strategy to energy planners and managers.

Effects of mechanical distribution on survival and reproduction of Phytoseiulus persimilis and Amblyseius swirskii

The application of beneficial organisms to protected crops requires substantial manpower and obliges operators to remain for long periods in a hot and humid environment that leads to discomfort and fatigue. Mechanisation of this operation could reduce the distribution time with subsequent benefits for the health and safety of workers. A prototype distribution system for beneficial arthropods that could increase labour productivity and distribution quality on protected crops was developed. Experiments were conducted to assess the efficiency of the mechanical distribution system and its effect on the distributed organisms. Releases of the predatory mites Phytoseiulus persimilis and Amblyseius swirskii were tested in the laboratory. The release quality was verified through evaluation of distribution patterns and the effects on the viability and fecundity of both beneficial arthropods. The prototype was shown to properly perform the release without compromising the quality and biological traits of either species.

Distribution system efficiency improvement using network reconfiguration and capacitor allocation

Distribution system utilities attempt to minimize cost with consideration of the system performance improvement. This paper employs the network reconfiguration and capacitor placement simultaneously to reduce energy losses and improve the system reliability subjected to satisfy operational and power quality constraints using a fuzzy approach. With respect to discrete and non-linear nature of the optimization problem, a Binary Gravitational Search Algorithm (BGSA) is utilized to solve the fuzzy multi-objective problem efficiently. The fast harmonic analysis method is used to perform harmonic power flow in the presence of shunt capacitors and non-linear loads. The state enumeration method based on Weibull–Markov stochastic model of the system components is adopted to assess reliability of different system configurations. Moreover, a new encoding strategy is proposed to boost the performance of network reconfiguration procedure. The IEEE 33-bus and an 83-bus practical distribution network of Taiwan Power Company (TPC) with a number of harmonic generating loads are utilized to test and validate the proposed method, and results are compared with Binary Particle Swarm Optimization (BPSO) algorithm and Binary Genetic Algorithm (BGA).

Unobserved Heterogeneous Effects in the Cost Efficiency Analysis of Electricity Distribution Systems

The purpose of this study is to analyze the cost efficiency of electricity distribution systems in order to enable regulatory authorities to establish price- or revenue cap regulation regimes. The increasing use of efficiency analysis in the last decades has raised serious concerns among regulators and companies regarding the reliability of efficiency estimates. One important dimension affecting the reliability is the presence of unobserved factors. Since these factors are treated differently in various models, the resulting estimates can vary across methods. Therefore, we decompose the benchmarking process into two steps. In the first step, we identify classes of similar companies with comparable network and structural characteristics using a latent class cost model. We obtain cost best practice within each class in the second step, based on deterministic and stochastic cost frontier models. The results of this analysis show that the decomposition of the benchmarking process into two steps has reduced unobserved heterogeneity within classes and, hence, reduced the unexplained variance previously claimed as inefficiency.

The High-Efficiency Isolated AC–DC Converter Using the Three-Phase Interleaved LLC Resonant Converter Employing the Y-Connected Rectifier

The power conversion efficiency of an isolated ac-dc converter is a dominant factor in the overall efficiency of dc distribution systems. To improve the power conversion efficiency of the dc distribution system, a three-phase interleaved full-bridge LLC resonant converter employing a Y-connected rectifier is proposed as the isolated ac-dc high-frequency-link power-conversion system. The proposed Y-connected rectifier has the capability of boosting the output voltage without increasing the transformer's turn ratio. Especially, the frequency of the rectifier's output ripple is six times higher than the switching frequency, thereby reducing the output capacitor and the secondary transformer's RMS current. However, the tolerance of the converter's resonant components in each primary stage causes the unbalance problem of output ripple current. It cannot be solved using conventional control techniques since the structure of the three-phase interleaving has the limitations of individual control capability for each converter. To solve the current unbalance problem, a current balancing method is proposed for the output rectifying current. The performance of the proposed converter and the current balancing method has been verified through experiments using a 10 kW (300 V/33.3 A) prototype converter.