Distribution System

Power system is a radial distribution system comprising large number of nodes and branches. Especially in Pakistan, large network causes power loss and voltage drop due to outdated infrastructure. Distributed Generation is one of the emerging solutions to compensate the load demand along with improvement in power quality and voltage profile of electrical power system. Although, proper placement and sizing of DG is still a challenging situation in power system as improper placement and sizing may bring the network more sever situation. This paper analyses a real time 11 kV radial distribution network of HESCO. An artificial intelligence technical named PSO is utilized to identify the optimal placement and size for DG integration. The proposed technique resulted as very effective for reduction in power loss with fast convergence.

در این پژوهش کوشیده ایم یکی از متداول ترین روش های توزیع در جهان را مورد بررسی قرار دهیم. توزیع
مویرگی یا سیستم توزیع فشرده و انبوه، امروزه به عنوان روشی موفق در توزیع محصولات شناخته شده است. به
طور کلی یکی از عناصر آمیخته بازاریابی که نقش تعیین کننده ای در موفقیت تولیدکنندگان در بازارهای صنعتی
دارد، سیستم توزیع است. همچنین با توجه به جهانی شدن و رقابتی تر شدن صنایع، نیاز به سیستم توزیع
یکپارچه و هماهنگ بیش از گذشته احساس می شود. امروزه توجه تولیدکنندگان به متغیرهای تاثیرگذار روی
ساختار کانال توزیع جلب شده و متناسب با آن به اصلاح، روزآمد کردن و طراحی جدید سیستم توزیع شرکت
خود می پردازند.
شرکت های پخش مویرگی نقش اساسی در توزیع کالا در سراسر کشور را بر عهده دارند. با توجه به موفقیت
چشمگیر پخش مویرگی در توزیع کالا به ویژه در بخش مواد غذایی و دارو، به بررسی علمی تر به منظور
تصمیم گیری برای انتخاب چنین سیستم توزیعی احساس می شود.
کلمات کلیدی: بازاریابی، پخش مویرگی، کانال توزیع، بازاریابی مویرگی، سیستم توزیع، سیستم توزیع فشرده و
انبوه

The development smart grids have made the power systems planning and operation more efficient by the application of renewable energy resources, electric vehicles, two-way communication, self-healing, consumer engagement, distribution intelligence, etc. The objective of this paper is to present a detailed comprehensive review of challenges, issues and opportunities for the development of smart grid. Smart grids are transforming the traditional way of meeting the electricity demand and providing the way towards an environmentally friendly, reliable and resilient power grid. This paper presents various challenges of smart grid development including interoperability, network communications, demand response, energy storage and distribution grid management. This paper also reviews various issues associated with the development of smart grid. Local, regional, national and global opportunities for the development of smart grid are also reported in this paper. 1. INTRODUCTION Smart grid (SG) technologies are vital to meet world's vast and growing electricity needs. Smart grids (SGs) are transforming the traditional way of meeting the electricity demand and providing the way towards an environmentally friendly, reliable and resilient power grid. Micro grids operate at the distribution level, and they are natural innovation zones for the Smart Grid (SG) because they have experimentation scalability and flexibility, and delivers power is a local area. SG contains protection against the cyber attacks, interoperability and designed for pricing in real-time [1]. Super grid is a high voltage DC transmission and capacity to minimize losses and enhance reliability. MGs operates as a standalone or as a grid-connected system. Microgrid (MG) technology is not equipped with automation and communication support. Further work is required to enhance self-healing, reconfigurable, adaptive and predictive capability. MG includes special purpose inverters enabling it to link to the legacy grid and contains special purpose filters build to overcome issues with harmonics, while improving power quality and efficiency [2]. Various characteristics of SG include optimizing the asset utilization and efficient operation is presented in [3]. Increased renewable power penetration, electricity markets participation throughout the world will realize new opportunities for the cost-effective smart grids controls and energy storage at all scales. These changes, coupled with increased consumer awareness and participation will lead to a new paradigm in energy system analysis that must also be accounted for energy security, stability and reliability. The SG will incorporates new networking technology, including controls and sensors, from this the electricity can be monitored in real time and can be made automatic changes which will reduce the energy waste [4].

In this paper a short-circuit computation (SCC) procedure for large-scale distribution systems with high penetration of distributed generators based on contemporary technologies is proposed. The procedure is suitable for real-time calculations. Modeling of modern distributed generators differs from the modeling of traditional synchronous and induction generators. Hence, SCC procedures found on the presumption of distribution systems with only traditional generators are not suitable in nowadays systems. In the work presented in this paper, for computation of the state of the system with short-circuit, the improved backward/forward sweep (IBFS) procedure is used. Computation results show that the IBFS procedure is much more robust than previous SCC procedures, as it takes into account all distribution system elements, including modern distributed generators.

El uso de la generación distribuida con fuentes de energías renovables no convencionales y de sistemas de almacenamiento de energía ha propiciado el cambio de los sistemas tradicionales de distribución de energía hacia las  microrredes  eléctricas.  La  idea  principal  de  esta  investigación,  es  analizar el comportamiento de una microrred por medio de su modelado y simulación usando el programa computacional OpenDSS. Para ello, se modeló el sistema de prueba IEEE de 13 nodos modificado por medio de la ubicación de sistemas de almacenamiento de energía y plantas de generación  -solar,  eólica  y  diésel-  distribuidas  en  diferentes  puntos  de  la  red  de  distribución.  Lo  anterior  permite  analizar  las  potencialidades  de  este  software,  así  como  las  técnicas  de  modelado  necesarias  para  su óptimo funcionamiento. Se verifica que el sistema, trabajando como microrred, mejora la eficiencia de la red de distribución en 51.5%.

A Static Compensator (STATCOM) is a flexible ac transmission system (FACTS) controller, which can either absorb or deliver reactive power to a power system. Distribution Static Compensator (DSTATCOM) is proposed for compensation of reactive power and unbalance caused by various loads (Sensitive and Non-Linear Loads) in distribution system. Distribution static compensator is based on the VSC principle. A D-STATCOM injects a current into the system to correct the voltage sag, swell and power factor. Distribution Static Synchronous Compensator (D-STATCOM) is an effective measure to maintain voltage stability and improve power quality of distribution system. An LCL filter has been used at the front end of a voltage source inverter (VSI), which provides better switching harmonics elimination while using much smaller value of an inductor as compared with the traditional L filter. A capacitor is used in series with an LCL filter to reduce the dc-link voltage of the DSTATCOM. This consequently reduces the power rating of the VSI. With reduced dc-link voltage, the voltage across the shunt capacitor of the LCL filter will be also less. It will reduce the power losses in the damping resistor as compared with the traditional LCL filter with passive damping. Therefore, the proposed DSTATCOM topology will have reduced weight, cost, rating, and size with improved efficiency and current compensation capability compared with the traditional topology. This paper deals with the modeling and control scheme of D-STATCOM. In this project by analyzing the different control techniques for designing the DSTATCOM & implementing the algorithm which will help in to design the model & working of DSTATCOM in MATLAB/Simulink for the required result.

As the number of users corresponding to distribution system has been increasing but it also gives birth to various problems like capacitor placement in the network, reducing the power loss, balancing the voltage level. Capacitor is a device which is used for transferring the reactive power and the main focus or aim is to reduce the loss and to improve the voltage profile. In order to solve all these problems there is a requirement of proper planning regarding installation of distributed system. The problem of capacitor placement in electrical energy distribution system involves determining the number, position, type and size of capacitors located on the distribution feeder, the total cost of system installation and operation, system load. This study provides an overview to the distributed power system along with its basic concepts.

"Evaluation of Physicochemical and Microbiological Parameters of Drinking Water Supplied from Distribution Systems of Kathmandu Municipality

Prabin Shakya1, Tista Prasai Joshi2, Dev Raj Joshi1 and Dwij Raj Bhatta1

1Central Department of Microbiology, Tribhuwan University, Kirtipur
2Research Laboratory, Environment Department, Nepal Academy of Science and Technology, Khumaltaar, Lalitpur

Corresponding author: Prabin Shakya, email address: prashal1@gmail.com, contact: 9841805371

ABSTRACT
Microbial pathogens in drinking water are primary cause in gastrointestinal and waterborne diarrheal diseases. Public health authorities still have not achieved success in controlling the most common waterborne diseases in Nepal. The objective of this study was to assess the quality of drinking water supplied from distribution system of Kathmandu. A total of 114 water samples were collected distributed from 4 distribution points. The physicochemical and microbiological analysis of water was conducted. Hetrotrophic plate count, detection of enteric pathogenic bacteria and Antibiotics susceptibility test were done. Distinct variations in physicochemical parameters were observed. The mean free residual chlorine was found 0.24mg/L. Total coliform were found in 61.4% (70/114) of water samples among which 15.7% (11/70) were found thermotolerant coliform. In distance, coliforms were found higher in far points (p=0.002). All thermotolerant coliform were found Escherichia coli. Mean HPC of water was found log103.15. The mean HPC of water (p=0.003) was found higher in far point. In collected samples, 10 different enteric bacteria were isolated in which E. coli was found most predominant followed by Pseudomonas spp., Citrobacter spp., Klebsiella spp., Shigella spp., Proteus spp., Enterobacter spp. Non-Typhii Salmonella spp., Providencia spp., Edwardsiella spp. In antibiotics susceptibility test, Gentamycin and Ofloxacin was found most efficient (100%) and least was found ampicillin (11.5%). Multiple antibiotics resistance was found in 5.3% of isolates.

Key words: heterotrophic plate count, coliform, multiple antibiotics resistance "

The use of cloud computing technology has been an important aspect in many applications in recent time. The cloud provides scalable and on-demand services to the customers and keeps the customer information and data secure. The overall performance of the cloud depends on the reliability, availability and standard of the resources. Even though the cloud provides many usefulness it faces many issues and challenges that needs to be handled. One such challenge is the efficient resource allocation to minimize the overall energy consumption. In this paper an efficient VM placement and allocation strategy is proposed for cloud datacenters to reduce the cost incurred for using the resources within the cloud datacenters. The proposed technique is implemented in the CloudSim toolkit where a simulation is done using sample cloud datacenters. The experimented results are noted down.

The distribution system is commonly broken down into three components: distribution substation, distribution primary and secondary. At the substation level, the voltage is reduced and the power is distributed in the smaller amounts to the customers. Consequently, one substation will supply many customers with the electric power. Thus, the number of the transmission lines in the distribution systems is many times that of the transmission systems. Furthermore, most customers are connected to only one of the three phases in the power distribution system. Therefore, the flow of the power on each of the lines is different and the system is typically 'unbalanced'. The electrical components in the power distribution systems are divided into six groups including overhead lines, underground lines, protective equipments, power transformers, distribution transformers, and capacitors. The failure of power distribution system may be due to failure of distribution transformers, mechanical damages, electrical circuits, magnetic circuits etc. that may lose the protections.

The introduction of distributed generation unit in distributed system improves the voltage profile and reduces the system losses. Optimal placement and sizing of Distributed Generation units plays a major role in reducing system losses and improving voltage profile .The different technical issues are combined using weighting coefficients and solved under various operating constraints using Particle Swarm Optimization with Time – Varying Acceleration Coefficient (PSO-TAC). In general Distributed generation is defined as generation of electricity within distributed networks. The distributed capacities minimize the requirement for over dimensioning of transmission and distribution system. If the value of the voltage stability index is increased system is increased significantly, then it is possible to operate the system away from voltage instability condition .The Particle Swarm optimization can be used to find the best location of Distributed Generation units considering voltage stability and short circuit level in the distribution system.

In an open electricity market environment, dispersed generation is predicted to play an important position. A high level of penetration and dispersion with distributed generators of an electric network imposes some additional problems; among them, of significant importance is the reconfiguration. The problem of reconfiguration has become more difficult because the customers ask more and more quality in power supply and reliability. The paper presents an original algorithm, aiming to find out the optimal open-looped points of electrical distribution networks with dispersed generation in order to obtain optimal radial configurations using Pareto optimality and evolution strategies.

Power losses and voltage drops severely impact the performance of home appliances and distribution transformers. Power loss is minimized to save electricity while the voltage level is maintained in allowable standard limits for the smooth operation of the power system. For this purpose, different techniques are discussed. Instead of utilizing traditional methods power engineers prefer to integrate renewable energy source(s) at optimal sites. In this paper, small scale solar photovoltaic modules are penetrated through the net-metering. The distribution feeder in district Khuzdar of Balochistan is taken as a case study for this research where irrigation loads of some optimal sites are solarized. Due to this integration of solar systems power loss is reduced while the voltage at consumers' ends is improved. This technique not only relieves the grid but also saves a huge amount of revenue. The solar PV systems are installed according to the demand of irrigation load. It is investigated that with the implementation of such small scale and a large number of solar PV units in the distribution scheme has declined the importance of large scale renewable grid integration. Performance analysis of existing and proposed distribution system has been carried out and the results obtained clearly demonstrates the effectiveness of the proposed method. The proposed systems are modelled in MATLAB/SIMULINK tool while the load flow analysis is performed in ETAP Software.

The electric power distribution system usually operates in a radial configuration, with tie switches between circuits to provide alternate feeds. The losses would be minimized if all switches were closed, but this is not done because it complicates the system’s protection against over currents. Whenever a component fails, some of the switches must be operated to restore power to as many customers as possible. As loads vary with time, switch operations may reduce losses in the system. Both of these are applications for reconfiguration. To get the distribution network to operate at its optimum performance in an automated distribution system reconfiguration was been proposed and researched. After feeder reconfiguration the losses of the radial system is found to be minimum but the buses has under voltage. To overcome this problem a optimal capacitor placement method is implemented. This will calculate the exact and optimal number of capacitor bank. This will help in reduction of losses...

In this paper a new connection for a unified power quality conditioner (UPQC) has been proposed to improve the power quality of two feeders in a distribution system. A UPQC consists of a series voltage-source converter (VSC) and a shunt VSC both joined together by a common dc bus. It is demonstrated how this device is connected between two independent feeders to regulate the bus voltage of one of the feeders while regulating the voltage across a sensitive load in the other feeder. Since the UPQC is connected between two different feeders (lines), this connection of the UPQC will be called an interline UPQC (IUPQC). The structure, control and capability of the IUPQC are discussed in this paper. The efficiency of the proposed configuration has been verified through simulation studies using MATLAB/SIMULINK.

Line loss evaluation of distribution system using artificial neural network (ANN) is presented in this paper. Due to the high capability of parallel information processing of the artificial neural networks, they have most suitable for line loss evaluation of distribution system. Back propagation algorithm is adopted for training of ANN. Feeder capacities in per unit are chosen as inputs to the ANN and distribution system losses are chosen as outputs. Training data are obtained from off-line load flow studies for different system topologies and load levels are carried out and the solution are complied to form the training set. The proposed algorithm is applied to 7-feeder distribution system and numerical results are presented in this paper in order to demonstrate the effectiveness of the proposed ANN algorithm in terms of accuracy. The developed ANN model can be utilized for both off-line simulation studies for performance evaluation and on-line energy loss evaluation

Distributed generation (DG) is an important issue for distribution networks due to the improvement in power losses, but the location and size of generators could be a difficult task for exact techniques. The metaheuristic techniques have become a better option to determine good solutions and in this paper the application of a bat-inspired algorithm (BA) to a problem of location and size of distributed generation in radial distribution systems is presented. A comparison between particle swarm optimization (PSO) and BA was made in the 33-node and 69-node test feeders, using as scenarios the change in active and reactive power, and the number of generators. PSO and BA found good results for small number and capacities of generators, but BA obtained better results for difficult problems and converged faster forall scenarios. The maximum active power injections to reduce power losses in the distribution networks were found for the five scenarios.

A microgrid is a small-scale smart network that contains distributed resources and loads and serves several technical, economic and environmental aims. In this kind of power system, the energy generated by the different sources is often collected in an adequate bus system (AC or DC busses), and transported to loads across a distribution system. In case of islanding operation of a microgrid, each production insufficiency or distribution system fault can cause a partial or total interruption of power supply required by loads of the microgrid. This unavailability can last longer because of the randomness and intermittent behaviour of renewable sources and the importance of the maintenance actions of the distribution system. To guarantee a high availability of power supply, microgrid must be able to produce and to transfer the power energy requested by loads. The sizing of distributed sources and the design of the distribution system present an important challenge to achieve this goal. The paper offers a new global methodology carried out in two steps: in the first, it aims to optimize the source sizing by adding some microsources for ensuring the balance between sources production and loads requirement, then, in a second
step, it aims to enhance the distribution system design by the creation of new paths of power transmission for transferring the produced energy from sources to loads. The proposed optimization methodology aims
to achieve the requested availability rate requested by each load (considering their priorities) by taking into account some technical and economic factors. In this methodology based on Genetic Algorithms,
objective functions are defined, and several electrical and economic constraints are formulated. The graph theory is used to represent the architecture of the microgrid distribution system, and Matpower tool of
Matlab is used to model it. An application and implementation of the proposed optimization methodology in a Tunisian petroleum platform indicate that the proposed solution is efficient in optimizing of power
supply availability in its microgrid

In this paper, the performance analysis of wind turbine as a distributed generation unit is presented. In this study a model of wind power is driven by an induction machine. Wind power that is distributed generation is capable of supplying power to ac power distribution network. Wind power generation system is modeled and simulated using Matlab Simulink software such that it can be suitable for modeling some kind of
induction generator configurations. To analyze more deeply the performance of the wind turbine system,both normal and fault conditions scenarios have been applied. Simulation results prove the excellent performance of the wind power unit under normal and fault conditions in the power distribution system

DG sources have been introduced as one of the most widely used and effective methods among various methods providing losses reduction in power systems. In this paper, the artificial bee colony algorithm has been employed with the aim of determining location and capacity of distributed generations (DGs) and capacitor banks (CBs) in distribution systems. The proposed objective function includes power losses and ENS reliability index, which is used by deploying weight coefficients as objective function in the algorithms. Accordingly, the standard 37-bus networks have been used for studies. The simulation results demonstrate that the artificial bee colony algorithm is more effective in all sections and has higher capability in reducing losses and improving reliability as well.

At present, energy distribution companies seek to improve service and implement alternatives to determine the capability of distribution system devices that allow to cover electric demand. This paper proposes a stochastic analysis to manage the demand response energy, depending on the voltage curve profiles established by historical measurements. The proposal is based on the stochastic prediction of energetic demand using Monte Carlo algorithms with Markov Chains (MCMC), from the analysis of the voltage profile as a deterministic variable. The analysis is associated with the prediction of the maximum power required to satisfy the peak demand period in distribution systems with predominance of residential load, also seeking the planning of the networks to increase efficiency, quality and reliability of power supply in peak hours, in order to reduce the contingencies in the operation of distribution networks in periods of peak demand, especially in systems where the residential load is predominant, which has been taking considerable growth, due to the insertion of electric cookers.

The integration of Electric Vehicles (EVs) in the distribution system is expected to rise within the following years posing technical challenges to the reliable operation of the electrical system. The increased use of EVs required a planned charging structure to minimize the disturbances and infrastructure augmentation in distribution system. Due to finite battery capacity and elongated charging time, it is essential to determine the optimal allocations of EV charging infrastructure in distribution system. This work presents the minimum increase in active power loss based optimal allocation of EV charging stations while maintain the prescribed power system constraints including voltage limits. The proposed methodology is demonstrated with IEEE 33 bus distribution system. In the optimization, Grey Wolf Optimization (GWO) algorithm is used. The results show the ef ectiveness of proposed methodology Optimal Allocation Provision for EV Charging Stations in the Low Voltage Distribution System