Conventional Distribution System Research Articles

ICT Enabled Public Distribution System for Developing Countries

Some Developing countries are facing severe problems now days which are hindering their speed of development and future prospects, Unrest in citizens or pubic institution due to corruption, less accountability and transparency government process. One of the burning problems is conventional Inefficient Public Distribution System and Ineffective Public Policy Implementation due to absence or ineffective feedback mechanism. Conventional PDS mechanism is viewed as linear transmission systems of benefits delivery. These PDS are top-down and hence struggle with quickly adapting to market dynamics and globalization. In this paper Prospect for social innovation with ICT emerges at the dynamic intersection of informal and conventional PDS and top down approach of services and goods delivery of the systems in the developing world. With the demographic changes developing countries are experiencing so it is time to utilize the ICT tools and mechanism to improve conventional PDS systems with model which is free from the severe loopholes like, leakage, unaccountability, transparency and feedback from bottom to top in timely manner and enhancing coverage of benefits in lower level of the population. New solutions needs to utilize Potential of ICT education in three ways: to increase ease of access and relevance of material through its integration into the PDS , leakage and introduce a feedback loop that enables players at all levels of the PDS and System itself to actively contribute to the design of the system. In this paper we are proposing ICT enabled Public distribution system model which can be implemented with the already existing PDS. Two Models on platform of ICT are proposed or developing countries ready having ICT enabled Identification of citizens and countries not having unique identification platform based on ICT. With the help of models, Paper is providing very effective way of benefit transfer and feedback mechanism to the problem of PDS in developing countries. This can be easily implemented if country is having exposure in ICT countries like India, Brazil, South Africa and Mexico.

Long-Term Maintenance Scheduling of Smart Distribution System through a PSO-TS Algorithm

Asset management of distribution systems is an important issue for smart grid. Maintenance scheduling, as an important part of asset management, affects the reliability of distribution equipment and power supply. This research focuses on long-term distribution system maintenance scheduling aided by available operation information, which is a prominent advantage of smart grid over conventional distribution systems. In this paper, the historical and future operation information in smart grid is taken into account through a decoupled time-varying reliability model of equipment. Based on distribution system reliability assessment, a maintenance scheduling model is proposed to determine the optimal implementation time of maintenance activities to minimize distribution systems’ total cost, while satisfying reliability requirements. A combined algorithm that consists of particle swarm optimization and tabu search is designed and applied to the optimization problem. Numerical result verifies that the proposed method can schedule long-term maintenance of distribution systems in smart grid economically and effectively.

An Improved Dispatch Strategy of a Grid-Connected Hybrid Energy System with High Penetration Level of Renewable Energy

As more and more renewable energy sources (RES) integrated into the conventional distribution system, how to make the current electric grid more reliable and efficient is becoming an important topic the world must face. In order to achieve these goals, grid-connected hybrid energy systems (HES) which contain battery energy storage systems (BESS) and many other advanced technologies have been developed and applied. Many benefits of BESS, such as high density of energy and power, have fast response in energy time-shift, frequency regulation, and so on. This paper focuses on the fluctuation alleviation and power quality improvement of grid-connected HES with high penetration level of RES. A multistage dispatch strategy of BESS for HES is proposed in this paper to mitigate the randomness and intermittence of the power flowed in HES because of high penetration level of RES integration. Four other conventional strategies are also discussed for evaluating the performance of the method proposed in this paper. Detailed cases and corresponding discussions are implemented, and the results show that the method proposed in this paper is more effective and robust than the other conventional strategies.

Passivity control via Power Shaping of a wind turbine in a dispersed network

The connection of renewable energy conversion systems in distribution networks must comply with codes for assuring power quality as well as the grid assistance demands. The new operating requirements cannot always be achieved from the control strategies that have been employed for years in conventional distribution systems. In this context, this paper addresses the problem of controlling a wind turbine from passivity control concepts. In particular a control strategy based on a new approach to the passivity theory, known as Power Shaping, is proposed. This approach allows to consider pervasive dissipation. The proposed strategy is evaluated in the context of extreme operating conditions showing capability to ride through grid failures. In this way, the simulation results encourage the application of concepts of Power Shaping in more complex systems of distributed generation.

Placement of Distributed Generation in 33/11 kV Radial Distribution System to Minimize Power Losses, Improvement in Voltage Profile and Reliability using Genetic Algorithm

Integration of renewable energy based distributed generation units provide potential benefits to conventional distribution systems. The power injections from renewable DG units located close to the load centers provide an opportunity for system voltage support, reduction in energy losses and reliability improvement. Therefore, the allocation of DG units should be carefully determined with the consideration of different planning incentives. In this paper, a simple method for real power loss reduction, voltage profile improvement which is based on voltage sensitivity index analysis is considered. Power flow analysis is done using the forward-backward sweep method, the placement and sizing of DG in distribution system are determined using optimization.The objective is to improve the reliability indices. The placement and size of DGs are optimized using a Genetic Algorithm. To evaluate the proposed algorithm, the 10 bus distribution feeder is used. The results illustrate the efficiency of the proposed method.

Comparison of optimal DG allocation methods in radial distribution systems based on sensitivity approaches

Integration of renewable energy based distributed generation (DG) units provides potential benefits to conventional distribution systems. The power injections from renewable DG units located close to the load centers provide an opportunity for system voltage support, reduction in energy losses, and reliability improvement. Therefore, the location of DG units should be carefully determined with the consideration of different planning incentives. This paper presents a comparison of novel, combined loss sensitivity, index vector, and voltage sensitivity index methods for optimal location and sizing of distributed generation (DG) in a distribution network. The main contribution of the paper is: (i) location of DGs based on existing sensitivity methods, (ii) proposing combined power loss sensitivity based method for DG location, (iii) modified Novel method for DG location, (iv) comparison of sensitivity methods for DG location and their size calculations, and (v) cost of losses and determining cost of power obtained from DGs and the comparison of methods at unity and lagging power factors. The results show the importance of installing the suitable size of DG at the suitable location. The results are obtained with all sensitivity based methods on the IEEE 33-bus and 69-bus systems.

Advanced Power Distribution System Configuration for Smart Grid

Power distribution systems should meet demands such as high reliability, efficiency, and penetration of renewable energy generators (REGs) in a smart grid. In general, power distribution systems are radial in nature. One-way power flow is the advantage of a radial system. However, the introduction of REGs causes bidirectional power flow. Furthermore, there are limits to improvements in reliability and efficiency in a radial system. Therefore, the upgrading of primary feeders from a radial to a loop configuration has been considered in the Korea Smart Distribution Project. An advanced power distribution system (APDS), in which primary feeders operate in a loop configuration, has been explored in this paper. First, the design scheme of a conventional power distribution system configuration that adopts distribution automation is introduced. Subsequently, an upgrading scheme of loop configuration using normally opened tie switches and a tie switch selection algorithm for loss minimization are described. Finally, the advantages of the upgraded configuration are reported through case studies. It is observed that the APDS configuration can integrate more REGs from the viewpoint of voltage regulation. An advanced distribution system allowing greater use of REGs will be a major contribution to smart grid implementation.

An approach for the integration of renewable distributed generation in hybrid DC/AC microgrids

This paper presents an investigation of a hybrid DC/AC integration paradigm to establish microgrids (MGs) by using a conventional three-phase local power delivery system. This approach adds an additional DC power line to the local power distribution system in order to collect energy generated by distributed domestic renewable sources. The local renewable distributed generation (DG) works in conjunction with the conventional grid utility to reduce the power draw from the grid. Researchers designed an energy conversion station to mix energy from the local DGs with energy from the grid utility. This approach, therefore, uses a continuous energy mixing strategy for DC integration of local generation and grid energy to supply energy to MG consumers via the conventional three-phase power distribution system. Thus, local distributed renewable generators do not have to contend with AC integration problems, such as AC stability and line synchronization. This approach can facilitate the transformation of conventional local power distribution systems into reliable MGs in an affordable way for stakeholders and it is a step towards construction of future smart grids.

Adaptive centralized protection scheme for distribution systems with DG using risk analysis for protective devices placement

Conventional electric distribution systems are radial in nature, supplied at one end through a main source. These networks generally have a simple protection system usually implemented using fuses, re-closers, and over-current relays. Recently, great attention has been paid to applying Distributed Generation (DG) throughout electric distribution systems. Presence of such generation in a network leads to losing coordination of protection devices. Therefore, it is desired to develop an algorithm which is capable of protecting distribution systems that include DG, through diagnosis and isolation of faults. A new approach for the protection of distribution networks in the presence of DGs is presented in this paper. The algorithm is based on dividing an existing distribution network into several zones, each capable of operating in island operation. In the suggested method, risk analysis is used to optimize the protection zones by optimal placement of protective devices. Multilayer Perceptrons (MLPs) neural networks are used for determination of faults. The proposed scheme has been implemented on a selected part of a real distribution network of a large city and a MATLAB based developed software has been used to implement the proposed algorithm on the real network data.

A Practical Protection Coordination Strategy Applied to Secondary and Facility Microgrids

In a conventional distribution system, protection algorithms are designed to operate on a unidirectional high fault-current level. In a microgrid, a fault current from distributed generation (DG) may bring about a relay malfunction because of the bidirectional and relatively small fault current. Therefore, the conventional protection scheme is not applicable to microgrids and a new protection method must be developed. In this paper, two protection coordination algorithms which can be applied for facility and secondary microgrids are proposed, respectively. The proposed protection algorithms eliminate faults not by the EMS signal but by directional relays. Moreover, this makes the algorithms flexible regardless of the types and numbers of DG. The proposed protection algorithms were simulated at the KEPCO RI Microgrid Demonstration Site.

An integrated energy, carbon, water, and economic analysis of reclaimed water use in urban settings: a case study of Austin, Texas

As water supplies become strained, some municipalities have turned to reclaimed water as a potential source to meet non-potable needs. Such reclaimed water – wastewater effluent treated to appropriate quality standards – is not suitable for human consumption without additional treatment, but can be used for purposes such as irrigation and cooling. One reclaimed water distribution system of particular interest is at the University of Texas at Austin (UT), USA, which receives treated effluent from City of Austin wastewater treatment plants. Depending on the embedded energy of existing water sources, existing levels of wastewater treatment, and the extent of the relevant distribution network, water reuse can save energy and carbon emissions compared with conventional drinking water distribution systems, at the expense of higher capital costs. Our analysis uses EPANet modeling software and historical datasets to examine the embedded energy and carbon emissions in drinking water and reclaimed water for non-potable applications at UT. We then examine the overall economics of reclaimed water use, including capital and operating costs for a variety of amortization periods, financing costs, and externality costs using a levelized-cost of water methodology. This integrated analysis serves as the basis for developing principles of sustainable water reuse.

Energy Benefit of the Underfloor Air Distribution System for Reducing Air-Conditioning and Heating Loads in Buildings

Although there have been continuing efforts recently for low-energy buildings as parts of the low-carbon green growth movement, particular attention has been paid to architectural design, the elective control of façades, and the efficiency of Heating, Ventilation, and Air Conditioning (HVAC) mechanical systems. To maximize the gains from these efforts, it is essential to consider the energy distribution approach and its layout during the design stage of the building. To this end, air distribution principles in HVAC have grown in popularity in buildings. The method to deliver the energy is strongly associated with increasing concerns about indoor environmental quality on occupants’ well-being, as well as rising energy costs for space heating and cooling. This paper identifies types of air distribution systems for heating and cooling in buildings and addresses the potential energy benefit of an underfloor air distribution (UFAD or UAD) system over the conventional ceiling air distribution system. A series of EnergyPlus simulations shows performance differences between the two distribution systems. One result is that the potential benefits of an UFAD are clearly demonstrated for a large space with a high ceiling.

Postharvest Performance of Selected Colombian Cut Flowers after Three Transport Systems to the United States

This study examined three transport systems used to transport fresh, non-stored cut flowers from Bogotá, Colombia, to the United States on a monthly basis for 1 year. Five cultivars of cut rose (Rosa hybrida), alstroemeria (Alstroemeria peruviana), carnation (Dianthus caryophyllus), and gerbera (Gerbera jamesonii) were commercially transported using a 7-day conventional distribution system with temperature controls and two rapid transport systems (3-day or 24-hour) with little or no temperature controls, respectively. Temperatures during the 24-hour transport system increased steadily and temperatures were at or above 10 °C for ≈18 h, with half of that time above 15 °C for all shipments. The 3- and 7-day systems had temperature fluctuations ranging from 3 to 24 °C and 3 to 19 °C, respectively. Flowers transported using the rapid transport systems had a significantly longer vase life compared with the 7-day transport in 83% of the shipments of alstroemeria and roses, in 58% of the shipments of carnations, and in 50% of the shipments of gerberas. Vase life increased 5.6% to 17.1% (0.7 to 2.1 days) for roses, 3.2% to 16.7% (0.5 to 2.7 days) for alstroemerias, 12.8% to 34.6% (1.1 to 6.2 days) for gerberas, and 4.6% to 8.8% (1.1 to 2.3 days) for carnations when using the rapid transport systems compared with the 7-day transport system. Some cultivars were more tolerant of the longer transport. The results show that when using fresh, non-stored flowers, the rapid transport systems had equal or longer vase life than the 7-day transport system in the majority of shipments for each flower species. Results also demonstrate that better temperature management during transport is a critical issue in the floral industry that needs to be improved upon.

Solid-state fault isolation devices: application to future power electronics-based distribution systems

This study addresses the timely issues of modelling, and defining selection criteria for, a solid-state fault isolation device (FID) intended for use in power electronics-based distribution systems (PEDS). This work subsequently derives the FID parameters by mapping the characteristics of a conventional medium-voltage distribution system onto that of the PEDS envisioned under a new multi-university Engineering Research Centre. When conventional circuit breakers are used in distribution systems, they have a relatively long clearing time, causing the voltage to collapse for a significant time. A semiconductor circuit breaker, however, is expected to be able to switch fast enough to keep a voltage disturbance within acceptable limits. The main focus of this study is to address the operational issues of the interaction between the power electronic converters and the solid-state FID. The utilisation of rate of current decrease (di/dt) control during turn-off in conjunction with passive clamping devices to manage the overvoltage that results from very fast circuit breaker operation is introduced. In contrast to a simple conventional RC-snubber circuit, the proposed overvoltage management avoids high leakage current, which is the undesirable drawback of RC-snubber circuits. The presented prototype is experimentally verified with low and medium-voltage test circuits.

연계형 풍력발전설비(225[kV], AC 링크방식)가 전력계통의 전원 품질에 미치는 영향에 관한 연구 분석

When small scale wind and solar power generation systems are connected to conventional power distribution system. It is worried that it can affect the quality of electricity such as voltage variation, power factor, frequency, harmonics and flicker. Therefore, in this research, in order to investigate the effects of wind power generation equipments(AC link method) on electrical power quality, when they are connected to distribution system. Power quality analyzer was installed respectively at the front side of power conversion system of conventional wind generation system and secondary side of consumer`s power supply at distribution line. Measurements on power quality were performed and the effects of the wind generation system on distribution system were analyzed when it was and was not operated. The results show that 0.34[%] increase on voltage variation, 0.145 increase on current crest factor and 0.6[] deviation on phase difference when the power generation system was operated.

Power Balancing Strategy in the Microgrid During Transient

When problems such as line fault, breakdown of a substation or a generator, etc. arise on the grid, the Microgrid is designed to be separated or isolated from the grid. Most existing DGs(Distributed Generators) in distribution system use rotating machine. However, new DGs such as micro gas turbine, fuel cell, photo voltaic, wind turbine, etc. will be interfaced with the Microgrid through an inverter. So the Microgrid may have very lower inertia than the conventional distribution system. By the way, the rate of change of frequency depends on the inertia of the power system. Moreover, frequency has a strong coupling with active power in power system. Because the frequency of the Microgrid may change rapidly and largely during transient, appropriate and fast control strategy is needed for stable operation of the Microgrid. Therefore, this paper presents a power balancing strategy in Microgrid during transient. Despite of strong power or frequency excursions, power balancing in the Microgrid can be maintained.

Evaluation of cost and reliability of power systems with large numbers of distributed generators

AbstractThe authors have proposed the Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for future power distribution systems. Also, a “micro grid” which is a similar concept to FRIENDS has been developed. In a micro grid, an independent distribution system can be constituted by a number of distributed generators. In this paper, FRIENDS, Micro grid, and conventional distribution systems are compared quantitatively in supply reliability and system cost through time sequential Monte Carlo simulations. In addition, for cost evaluation, interruption costs are included to show risk incurred by unsupplied energy. Finally, the authors search for preferable form with install and operation of distributed generators and network composition according to social cost including interruption cost and system cost. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 28–37, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20659

Lightning and Surge Protection in Photovoltaic Installations

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The aim of this paper is to give scientific background and essential assumptions to be introduced into the design of lightning and surge protection in photovoltaic installations (PVIs), with particular emphasis on the aspects of standardization to be covered. For this purpose, the relevant protective measures given in the standards for conventional low-voltage power distribution systems (CLVPDSs) are adapted in part. This revision is required because the peculiar characteristics of PVIs are different from those of CLVPDSs. The resulting protection approach that determines the advisable protective measures by a risk management has been applied to an actual grid-connected PVI (GCPVI), Univer Project. The extra cost of this protection in this PVI (approximately 3.6% of the system cost) is of secondary importance because of the increase of safety and availability. Furthermore, in order to fulfill with this protection, the surge withstand capability (SWC) of PV modules has been investigated as well. </para>

Determination of particle concentration in the breathing zone for four different types of office ventilation systems

Many factors affect the airflow patterns, thermal comfort, contaminant removal efficiency and indoor air quality at individual workstations in office buildings. In this study, four ventilation systems were used in a test chamber designed to represent an area of a typical office building floor and reproduce the real characteristics of a modern office space. Measurements of particle concentration and thermal parameters (temperature and velocity) were carried out for each of the following types of ventilation systems: (a) conventional air distribution system with ceiling supply and return; (b) conventional air distribution system with ceiling supply and return near the floor; (c) underfloor air distribution system; and (d) split system. The measurements aimed to analyse the particle removal efficiency in the breathing zone and the impact of particle concentration on an individual at the workstation. The efficiency of the ventilation system was analysed by measuring particle size and concentration, ventilation effectiveness and the indoor/outdoor ratio. Each ventilation system showed different airflow patterns and the efficiency of each ventilation system in the removal of the particles in the breathing zone showed no correlation with particle size and the various methods of analyses used.

On-Chip Power Distribution Grids With Multiple Supply Voltages for High-Performance Integrated Circuits

On-chip power distribution grids with multiple supply voltages are discussed in this paper. Two types of interdigitated and paired power distribution grids with multiple supply voltages and multiple grounds are presented. Analytic models are also developed to estimate the loop inductance in four types of proposed power delivery schemes. Two proposed schemes, fully and pseudo-interdigitated power delivery, reduce power supply voltage drops as compared to conventional interdigitated power distribution systems with dual supplies and a single ground by, on average, 15.3% and 0.3%, respectively. The performance of the proposed on-chip power distribution grids is compared to a reference power distribution grid with a single supply and a single ground. The voltage drop in fully interdigitated and fully paired power distribution grids with multiple supplies and multiple grounds is reduced, on average, by 2.7% and 2.3%, respectively, as compared to the voltage drop of an interdigitated power distribution grid with a single supply and a single ground. The proposed power distribution grids are a better alternative to a single supply voltage and a single ground power distribution system. On-chip resonances in power distribution grids with decoupling capacitors are intuitively explained in this paper, and circuit design implications are provided. It is also noted that fully interdigitated and fully paired power distribution grids with multiple supply voltages and multiple grounds are recommended to decouple power supply voltages.