Power system distribution

Power quality is one of the major problems in the present era. It has gained its importance because of the introduction of the sophisticated devices, whose performance is very sensitive to quality of power supply. Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure of end user equipment. One of the major problem dealt here is the voltage sag of the multiline power system. The aim of this paper is to design an Interline Dynamic Voltage Restorer which is able to compensate voltage sag and voltage regulation at critical load terminals. In our project, the Interline Dynamic Voltage Restorer (IDVR) has two IDVRs are connected to a common DC Link with Adaptive Neuro-Fuzzy Inference System (ANFIS). One of the IDVRs compensates for a voltage sag, the other IDVRs connected to common DC-Link energy storage. A current mode control strategy is incorporated into the IDVR system in both the working modes, voltage sag compensat...

Проблема преднамеренных электромагнитных деструктивных воздействий (ПЭДВ) на энергосистемы становится в последнее время все более и более актуальной в связи с двумя современными тенденциями: расширяющимся применением микроэлектроники и микропроцессорной техники в электроэнергетике, с одной стороны, и интенсивной разработкой специальных технических средств, предназначенных для дистанционного разрушения микроэлектроники, -с другой. Самым мощным средством разрушения микроэлектроники является электромагнитный импульс высотного ядерного взрыва (ЭМИ ЯВ). История экспериментов с ЭМИ ЯВ насчитывает уже полвека. За это время были написаны многие десятки статей, книг, отчетов, стандартов, детально описывающих явление ЭМИ ЯВ, его влияние на электронную аппаратуру и электроустановки, а также средства защиты от него. Однако большинство гражданских специалистов во многих областях техники по-прежнему остаются в неведении относительно этого феномена и средств защиты от него. Целью данной публикации является предоставление гражданским специалистам информации о доступных в Интернете стандартах и отчетах по данной теме, которые они могут использовать при оценке опасности ЭМИ ЯВ для силового электрооборудования и электронных приборов энергосистем и разработке средств защиты. 1. Стандарты Международной Электротехнической Комиссии (МЭК): 2. Стандарты Института инженеров электриков и электронщиков США (IEEE) 3. Стандарты Европейской Комиссии 4. Военные стандарты США 5. Стандарты НАТО ОТЧЕТЫ 1. Теория ЭМИ ЯВ 2. Геомагнитно-индуцированные токи и их влияние на энергосистему 3. Влияние ЭМИ ЯВ на энергосистему

This paper presents an overview analysis and a discussion of field experience with different drive configurations used in shovel applications. The analysis includes different drive topologies, shovel duty cycles for a typical truck pass loading and energy regeneration capabilities. Special attention is given to the interaction between the high power shovel drives and the grid: harmonics injection, reactive power requirements, and voltage regulation. This paper presents operational experiences obtained in copper mine industries. The main characteristics of the newest shovels with Active Front End (AFE) at the line side are also included. Finally, a critical evaluation of the different topologies is presented, showing that the shovel drive operation strongly affects the behavior of the power distribution system and that the introduction of the AFE technology produces an important performance improvement.

The paper proposes a near-optimal, distributed implementation of the particle filter for large scale dynamical systems with sparse measurements, as in wireless sensor networks (WSN) and power distribution systems. Compared to the centralized approach, the distributed implementation of the particle filter is computationally efficient and provides considerable transmission bandwidth savings due to a significant decrease in information exchange between the neighbouring nodes. In our test simulations, the performance of the distributed implementation is almost indistinguishable from the centralized particle filter.

CHAPTER ONE 1.0 INTRODUCTION 1.1 BACKGROUND OF THE STUDY Energy theft is a significant problem facing the Nigerian power sector, leading to substantial revenue losses, poor power quality, and increased operational costs. The widespread illegal connections, meter tampering, and billing irregularities undermine the efficiency and reliability of electricity supply. To address these challenges, the implementation of prepaid meters has been proposed as a viable solution. Prepaid meters allow consumers to pay for electricity before use, thereby promoting efficient energy consumption and reducing the incidence of energy theft. By providing real-time monitoring and control over energy usage, prepaid meters can help utility companies ensure accurate billing and minimize losses. In Nigeria, various electricity distribution companies, including Ikeja Electric, have begun adopting prepaid meters to enhance service delivery and curb energy theft.

In this study, a novel sinusoidal PWM Switched Power Filter (SPF) and Dynamic Voltage Compensation (DVC) scheme using VSC/SMC/B-B controller for power mitigation and quality enhancements in medium power distribution systems are simulated. The system is based upon a stand-alone Wind Energy Conversion Scheme (WECS) using an induction generator and the proposed system control mechanisms, which are digitally simulated by using the MATLAB/Simulink/SimPowerSystems software.

The frequency stability of a power grid is effectively managed through the inertia and power reserves supplied by synchronous generators. Due to increasing concerns about the greenhouse effect and global warming, renewable energy sources (or microgrids) are increasingly replacing traditional fossil fuel-based methods of electricity generation. As microgrid deployment proliferates, power systems' inherent complexity and non-linear dynamics have escalated, rendering conventional controllers inadequate across diverse operating conditions. Factors such as reduced energy inertia, heightened penetration of renewable energy sources, and significant power fluctuations within confined transmission systems have heightened the vulnerability of microgrid frequencies to instability. This paper elucidates the concept of microgrids, examines frequency fluctuations in the presence of solar and diesel generators alongside load variations, and presents simulation-based analyses. Moreover, it provides a succinct overview of frequency control methodologies. Validation outcomes demonstrate the efficacy of the proposed controller in maintaining system frequency amidst fluctuating load demands and renewable energy inputs.

The orderly and rapid restoration of the distribution system (DS) after disasters relies on the accuracy and reliability of fault location. Disasters may also damage communication infrastructure, e.g., wireless base stations, resulting in failure to report fault information detected by remote fault indicators (RFIs) in a timely manner. By utilizing the emergency wireless communication via unmanned aerial vehicles (UAVs), this paper proposes a UAV-assisted communication restoration and fault location coordinated strategy. Designing multiple objectives, the strategy co-optimizes the communication restoration and fault location to get the UAVs’ flight trajectory as well as to identify the fault location and RFI abnormalities. The proposed method is verified for accuracy and validity by applying it to the IEEE 33-node system.

The traditional service restoration methods are experiencing a significant challenge because the performance of such methods is often dominated by very large processing time. Therefore, it is important to develop a fast and an accurate method to solve a complex non-linear optimization problem representing the service restoration problem in a distribution system. In this paper, due to a binary nature of the service restoration problem, the Binary Water Cycle Algorithm (BWCA) is proposed to reduce out-of-service loads and system losses considering operational constraints, the radial topology of the distribution systems, and the influence of the presence of distributed generations (DGs) on the service restoration problem. The proposed method is a modified form of the Water Cycle Algorithm (WCA) that is mainly used for discrete and continuous optimization problems. The effectiveness of the proposed method is validated by comparing with other well-known meta-heuristic algorithms using a modified IEEE 33-node radial distribution system. The simulation results demonstrate the robustness of this method to provide a precise decision with short convergence time for solving service restoration problems.

This paper presents the application of quantitative and qualitative methods to assess reliability and security in urban electrical substations. The method is a visual technique based on a conceptual analysis of the different substation configurations. We also performed a sensitivity analysis considering the effects of connecting and disconnecting various elements of a power system. The procedure considers evaluating the loadability levels of transformers, buses, and lines, as well as the current state of the individual elements and the number of connected elements. A new index was proposed for urban electrical substations, evaluating the non-attended demand risk. The technique was tested in a power system case study with a meshed subtransmission network and distribution circuits to supply power to the loads. The results showed that the proposed method is a useful qualitative method to obtain a quantitative description of the system during operation in critical cases and the non-attended demand risk. In addition, 30% of the electrical substations showed low reliability indicators for critical cases such as failures in transformers that connect different internal configurations. These findings could be of interest for utilities and operators, as this document provides a simplified and graphic method that can integrate components such as configurations, non-attended demand risk, and loadability indicators as key parameters to identify critical points that affect the reliability and security of power systems. The case study showed that the electrical substations with the highest non-attention demand risk, around 50%, were those with single-and double-bar configurations in their respective switchyards. On the other hand, the substations with the lowest risk of unmet demand, equal to or less than 20%, were electrical substations with a doublebar + bypass switch configuration, a double-bar and ring configuration in the 110 kV switchyard, and a single-bar configuration in the 13.8 kV switchyard. This study showed that those substations that had couplings had a higher probability of withstanding contingencies.

This paper presents the application of quantitative and qualitative methods to assess reliability and security in urban electrical substations. The method is a visual technique based on a conceptual analysis of the different substation configurations. We also performed a sensitivity analysis considering the effects of connecting and disconnecting various elements of a power system. The procedure considers evaluating the loadability levels of transformers, buses, and lines, as well as the current state of the individual elements and the number of connected elements. A new index was proposed for urban electrical substations, evaluating the non-attended demand risk. The technique was tested in a power system case study with a meshed subtransmission network and distribution circuits to supply power to the loads. The results showed that the proposed method is a useful qualitative method to obtain a quantitative description of the system during operation in critical cases and the non-attended demand risk. In addition, 30% of the electrical substations showed low reliability indicators for critical cases such as failures in transformers that connect different internal configurations. These findings could be of interest for utilities and operators, as this document provides a simplified and graphic method that can integrate components such as configurations, non-attended demand risk, and loadability indicators as key parameters to identify critical points that affect the reliability and security of power systems. The case study showed that the electrical substations with the highest non-attention demand risk, around 50%, were those with single-and double-bar configurations in their respective switchyards. On the other hand, the substations with the lowest risk of unmet demand, equal to or less than 20%, were electrical substations with a double-bar + bypass switch configuration, a double-bar and ring configuration in the 110 kV switchyard, and a single-bar configuration in the 13.8 kV switchyard. This study showed that those substations that had couplings had a higher probability of withstanding contingencies.

In Lithuania energy system are places where the electric field strength exceeds the value set in EU Directive 2013/35/EU. These zones could be set by analytical or numerical modelling. Hazardous zones could not be only under the high voltage wires but near the fences, other low-level connected to earth structures which are located near the high voltage power lines as showed by investigation. Algorithm for high voltage dangerous zones investigation is proposed.

This paper presents a new procedure to analyze power distribution systems that energize nonlinear loads. The algorithm uses the singular values of the transfer matrix that relates the output variables and the system perturbation. The algorithm is especially developed to analyze the compensation performance of shunt and series active power filters. The algorithm is proved by simulation in a multibus industrial power distribution system and programmed in Matlab.

This paper presents the performance analysis of a hybrid filter composed of passive and active filters connected in series. The analysis is done by evaluating the influence of passive filter parameters variations and the effects that different active power filter's gain have in the compensation performance of the hybrid scheme. The compensation performance is quantified by evaluating the attenuation factor in a power distribution system energizing high-power nonlinear loads compensated with passive filters and then improved with the connection of a series active power filter. Finally, compensation characteristics of the hybrid topology are tested on a 10-kVA experimental setup.

In the last few decades, the Smart Grid paradigm presence has increased within power systems. These new kinds of networks demand new Operations and Planning approaches, following improvements in the quality of service. In this sense, the role of the Distribution Management System, through its Outage Management System, is essential to guarantee the network reliability. This system is responsible for minimizing the consequences arising from a fault event (or network failure). Obviously, knowing where the fault appears is critical for a good reaction of this system. Therefore, several fault location techniques have been proposed. However, most of them provide individual results, associated with specific testbeds, which make the comparison between them difficult. Due to this, a review of fault location methods has been done in this paper, analyzing them for their use on underground distribution lines. Specifically, this study is focused on an impedance-based method because their requirements are in line with the typical instrumentation deployed in distribution networks. This work is completed with an exhaustive analysis of these methods over a PSCAD TM X4 implementation of the standard IEEE Node Test Feeder, which truly allows us to consistently compare the results of these location methods and to determine the advantages and drawbacks of each of them.

In Colombia there are two indexes to measure the power supply continuity: DES and FES. DES stands for equivalent duration of the interruptions, ie. total time without power supply; meanwhile, FES stands for equivalent frequency of the interruptions, ie the total number ...

Growing widespread outages in power systems caused by natural disasters have highlighted the necessity of applying defensive approaches with the goal of prompt service restoration. In this context, this paper proposes a stochastic model with the goal of optimally using proactive operational actions before the upcoming disturbance hits. The actions considered in this study include network reconfiguration and crew prepositioning. To take the effective actions, the model simulates probable damages caused by the events via a set of scenarios generated by Monte Carlo simulation method. The proposed model aims at minimizing the expected load curtailment caused by the event over the scenarios. To calculate the amount of load curtailments, potential post-disturbance actions are also considered in the model. The model is mathematically formulated in mixed integer linear programming (MILP) fashion which can be easily solved via available software packages. A standard distribution system with a realistic set of data is employed to validate the effectiveness of the proposed model.

In order to realize the Smart Grid vision, it is necessary to have guaranteed Quality of Service (QoS) for the communication and networking technology used in various stages of the Smart Grid, ranging from power generation, transmission, distribution, to the customer applications. The low cost wireless protocols such as Zigbee (using IEEE 802.15.4 defined physical and MAC layer) and Bluetooth (IEEE802.15.1) are especially useful for the power distribution system monitoring and customer applications. However, they do not support QoS and typically have a short propagation distance. In this paper, we propose to add the QoS into these low cost protocols by providing differentiated service for traffic of different priority at the MAC layer and use Zigbee as an example. Our analytical delay model and simulation results show that the proposed QoS enhancement can improve the delay and goodput of the network, thus ensuring the reliability, availability, and performance of a Smart Grid distribution monitoring and control.

This study assessed the impacts of natural phenomena-induced electrical faults on the distribution system of Lagos, served by Ikeja and Eko electricity distribution companies. The research evaluated the frequency, technical, cost, and reliability impacts of these faults. The study employed statistical and software-based short circuit fault analyses as well as system reliability indices methods to identify the most vulnerable feeders to nature-induced faults. It also simulated the network's response to fault currents and estimated the monthly costs of nature-induced outages. For the data period, an average of 20 to 43 nature-induced faults occurred annually on the networks. The obtained fault currents ranged from 0.67kA to 0.78kA and 0.52kA to 1.02kA for the 11kV and 33kV networks, respectively, which was useful for setting up installed breakers. The estimated average monthly cost of nature-induced energy loss was found to be between ₦3 million and ₦143 million for Eko and between ₦0.01 million and ₦108 million for Ikeja. The System Average Interruption Frequency Index and System Average Interruption Duration Index did not exceed 4 and 60, respectively, on 33kV network. In conclusion, natural phenomena-induced electrical faults had significant impacts, particularly in terms of monthly costs and investments in its mitigation should be explored.

The distribution system is essential in the provision of electricity for all consumers. However, outages occasioned by faults are a major setback in ensuring a regular supply of electricity to consumers in a populous state like Lagos. This study analyses the outage causes, their cost, energy loss, and duration of outages experienced by electricity consumers in the distribution systems of Lagos State. The fault reports of Eko Electricity Distribution Company (EKEDC) and Ikeja Electricity Distribution Company (IKEDC) were used for the analysis. The analysis revealed that the main causes of outages on the network are transient faults (356.78 occurrences per month) and jumper cuts (352.83 occurrences per month). The average monthly cost impacts of the outages on the network are estimated to be between ₦631m & ₦837m and ₦837m & ₦1.66b for the 11kV and 33kV networks of the State respectively. The average monthly energy lost due to outages on the network for the period under review is sign...

A highly controlled and automated life support system has long been a NASA goal. It is usually assumed that life support for future long duration missions will use physical/chemical recycling systems that substantially close the oxygen and water circulation loops. Such a tightly coupled life support system has been thought to require an overall supervisory control system to minimize crew operation and maintenance activities. The International Space Station (ISS) Environmental Control and Life Support System (ECLSS) was at first expected to have supervisory control and automation. After this was found infeasible during the design of the ISS ECLSS in the early 1990's, it was then expected that the ISS or future mission systems would be upgraded to meet the original expectations. Since then NASA has extensively researched life support system controls and automation. Automation and Artificial Intelligence (AI) have gone through several cycles of enthusiasm and neglect before their recent great achievements, and NASA life support interest has similarly varied. Since the ISS ECLSS was launched, its on-board operational problems have led NASA to deemphasize system level controls and automation in favor of improving subsystem reliability and maintainability. Recent work has investigated supervisory control for a system similar to the ISS ECLSS. This paper reviews past planning and work on the supervisory control of closed, integrated physical/chemical life support systems similar to the ISS ECLSS and its precursors dating back to the 1960's.

This paper presents the preliminary results of an undergoing study about the implementation of RFID technology in the shoe industry in Ecuador. As a starting point, descriptions about the benefits and limitation of RFID and the logistics scenario in Ecuador are provided. Then, the implications of adopting RFID along the entire shoe supply chain are discussed, including two governmental control agencies. Finally, some additional considerations such as implementation challenges and financial implications are discussed.

With the significant increase in renewable energy sources (RES) and storage elements, power distribution system needs new services for reliable and continuous operation. Smart transformer (ST) based on power electronics, control, and communication has been proposed for improving the performance of power system. However, operational capabilities and applications of ST with RES and energy storage in distribution system are still not explored in detail. In this paper, a new prospective of ST application, dual microgrid (DMG) operation, is proposed. In normal medium voltage (MV) grid operation, the ST supplies power to loads connected to its low voltage side and injects into the MV grid depending upon the available RES and load demand. During the voltage disturbances, the ST feeds power to the sensitive loads connected to the other feeders equipped with the conventional power transformers. In this case, the distribution loads are isolated from the MV utility grid. This ability of the smart transformer to isolate from the utility grid and provide continuous power to the sensitive loads of other feeders has potential to significantly improve the performance of power system as well as ST. With simulation results based on PSCAD/EMTDC software, this paper introduces for the first time an unexplored feature of the smart transformer. Index Terms-Smart transformer (ST), dual microgrid (DMG), power distribution system.

A three-phase distribution system state estimation algorithm is proposed in this paper. Normal equation method is used to compute the real-time states of distribution systems modeled by their actual a-b-c phases. A current based formulation is introduced and compared with other formulations. Observability analysis for the proposed distribution system state estimation is discussed. Test results indicate that the normal equation method is applicable to the distribution system state estimation and the current based rectangular form formulation is suitable for this application.

The Use of FACTS Options to Permit Utilization of the Full Thermal Capacity of AC Transmission Long distance transmission of electric power permits serving loads with lower cost energy than may be available locally. For such economic reasons, most if not all of the world's electric power supply !systems are widely .interconnected, involving interconnections inside utilities' own territories. These interconnections extend to inter-utility and then to interregional connections. Due to a variety of environmental, land-use and regulatory pressures, the growth of electric power transmission facilities in many parts of the world is restricted, even though bulk power transfers and access by third parties are on the increase. The result is transmission bottlenecks, non-uniform utilization of facilities and unwanted parallelpath or loop flows. Often as power transfers grow, the power system beco:mes increasingly more complex to operate, and the system can become more insecure with large power flows with inadequate control. Th.e other aspect of the problem then becomes the inability to utilize the full potential of tran~mis~sion interconnections. With this in mind, the Electric Power Research Institute (EPRI), representing the collaborative research and development arm of the utility industries in the US, is supporting the development of FACTS (Flexible AC Transmi:ssion System) technologies. It has been discussed through publications , in speeches at IEEE meetings, forums, workshops, CIGRE, various utilities and most recently at a highly successful International Conferer~ce in Cincinnati in September 1990, organized by EPRI. The

This thesis analyzès and tests some néw solution techniques for the optimal power flow problem. This new methodology exploits a parametric technique, callp-d the continuation method, which is applied to different tasks in the solution procedure. In a first application, th'e continuation method l solves the-quadratic subp:t;oblems generàted sequentially by the optimal power • flow's nonlinear program. 'lt first creates a simple subproblem, which' is easy to solve, and then links it to the subproblem we wish to solve. Starting a~ the solution of the simpte problem, it generates optimal solution trajectories for the intermediate problems, leading to the desired optimal solution. Solution times are often advantageous, because this technique avoids the lengthy combinatorial search required in conventional methods to locate the set of active constraints. very useful in themselves. Furthermore, the solution trajectories are often In a second application, the algorithm tracks optimal solutions trajectories of the nonlinear problem when the load i5 slowly. varied. This constitutes an ex~mple of "incremental loadin& '. a technique already used for real power dispatch, but in this case a complete network model is used. The flexibility of the algorithm at various levels aHows for s~lI!e excellent computation times in this load-tracking mode: we have observed reductions in computation times for new solutions of the order of 70%, compared to the computation time of the initial load. This thesis first presents an analysis of the various structures used in optimal power flow algorithms. Then, having chosen and presented the structure of our algorithm, we analyze the quadratic subproblems generated by this algorithm for sorne of its more important tasks: minimum cost, minimum losses and load shedding. New rules are proposed to link the solutions of successive subproblems to erwure the convergence of the nonlinear problem. Then, as a final contribution to the theory, some extensions are suggested for the subproblems: among them are ramp constraints, bus incremental costs, and ~ provisioml for redf'spatching. Numerical simulations of the proposed optimal power flow algorithm using the minimum fuel cast task were performed 'on four test systems. with sizes • c " 11 , 'J, ranging from 6 to 118 \ buses. The resu1ts are documented in detai1, and ~ resu4:.s for the 30 bus test are compared to those reported by other authors.

Compared to yesteryear, non-linear loads now proliferate in homes, offices and the industrial environment. Non-linear loads now form a major component of the total loading in the typical electrical network. The Compact Fluorescent Lamp is but one example of a non-linear load that inherently produces and injects distorted currents into the electrical power network, which could create adverse consequences if appropriate and adequate harmonic mitigation techniques are not employed. CFLs are now a major component of the luminaires market around the world because consideration is being given worldwide to the phasing out of incandescent lamps. However, there are legitimate concerns over the quality of some CFLs. This paper investigates and compares the quality of some major brands of CFLs, in terms of parameters such as harmonic content, power factor, fundamental power factor, nonactive power, and apparent power. The wider implication of these results is ascertained by investigating the e...

The increasing prevalence of distributed generation, particularly photovoltaic (PV)-based sources, in electricity distribution networks underscores the need for comprehensive studies on their impact on network operation. This paper addresses the significance of leveraging PV inverters to provide both capacitive and inductive reactive power support, thereby reducing the necessity for additional investments. By incorporating PVs in this dual role, the distribution network gains enhanced flexibility in managing voltage profiles, reducing dependency on additional investments in infrastructure. This dual functionality addresses the dynamic needs of the grid, offering a sustainable solution to optimize the network's overall performance while harnessing the inherent capabilities of PV technology. In this investigation, Python-based Particle Swarm Optimization (PSO) and Firefly algorithms (FA) have been applied to ascertain the optimal amount of reactive power support for enhancing the voltage profile of the network, and the effectiveness of the algorithms are compared. The algorithms take into account the reactive power limits inherent in PV plants within the distribution network, and optimize the reactive power support that should be taken from each PV that won’t result in any curtailment in PVs’ active power generation, i.e., only the remaining capacity of the inverter is allowed for the reactive power support, if needed. The network is modeled, analyzed, and simulated using the DIgSILENT PowerFactory program, with seamless integration between the network model and the optimization algorithm facilitated through Python. The obtained results demonstrate that reactive power support from PV plants yields positive effects on the overall voltage profile of the network.

This article introduces a novel approach to enhance the performance of LCL based active power filters (APFs) in four-wire distribution systems by employing a nonlinear current control strategy. The strategy combines backstepping control (BSC) and a nonlinear disturbance observer (NDOB) to effectively manage harmonic and interharmonic grid currents. By situating the shunt active power filter (SAPF) at the point of common coupling (PCC) via the LCL filter, the technique ensures that grid connected currents remain balanced and purely sinusoidal. The integration of NDOB with BSC aims to fortify the resilience of BSC against disturbances. Consequently, any disturbances occurring within the system are precisely estimated by the NDOB and subsequently mitigated through the BSC mechanism. Notably, this approach showcases robust adaptability across diverse scenarios, encompassing external disturbances, variations in filter parameters, nonlinear loads laden with harmonics and interharmonics, load imbalances, and non-ideal grid voltages. Its performance remains robust and stable even when disturbances are present. Comparative analysis with linear-based methodologies underscores the advantages of this approach, revealing quicker and smoother transient responses. The efficacy of the proposed technique is demonstrated through comprehensive simulation studies, substantiating its potential for significantly advancing power quality in complex distribution systems.

In this paper a statcom is developed to improve the power quality in a dc traction system. The proposed statcom can be used as both inverter and active filter. As an active filter , it can compensate harmonic distortion and reactive power and as an inverter, it can recycle regenerative energy caused by decelerating trains. The simulation results are carried out by using PSCAD/EMTDC software.

Most of the in-plant medium-voltage generators are grounded through resistors ranging from 200 to 400 A. In some unusual situations, the resistors may even be as high as 1200 A. Low-resistance grounding is a preferred choice for a medium-voltage power distribution system. However, extensive generator stator ground fault damages had been reported due to the prolonging generator neutral ground current, which would continue to flow even after the main and field breaker opened. This ground fault current could continue to flow for as long as 5 s depending on the generator open-circuit time constant. As a result, the higher the generator neutral current, would lead to the higher stator ground fault damages. An IEEE Working Group has recently completed its study and made recommendations for medium-voltage generator grounding in a multiple source industrial environment. Based on the considerations of transient overvoltage, ground fault damages, and ground fault protection, the working group suggests a few variations of grounding systems, which basically are low-resistance grounding systems during normal operating conditions, and the generator would be switched to a high-resistance grounded system from a normal low-resistance grounded system when a ground fault occurs in the generator stator. The purposes of this paper are: 1) to examine the generator transient over-voltage and currents under the low-resistance ground fault conditions, and also to evaluate their corresponding stator ground fault damages, and 2) to establish an acceptable maximum system ground fault level. For comparison purposes, three versions of low-resistance grounding systems have been considered and they are: a low-resistance grounding system with a neutral breaker at the generator (hereinafter called a "neutral breaker system"); a low-resistance grounding system with the generator neutral low resistor being switched to a high-resistor after a stator ground fault (hereinafter called a "hybrid system"); and a low-resistance grounding system similar to the current practice (hereinafter called a "traditional system"). The simulation study is conducted with the aid of the Electro Magnetic Transient Program. An experimental analog generator model is also used to verify the simulation results. Index Terms-Neutral breaker grounding system and hybrid grounding system, stator ground fault damage, transient overvoltage.

The paper describes a new power distribution system for Fermilab's Main Injector. The system provides 13.8 kV power to Main Injector accelerator (accelerator and conventional loads) and is capable of providing power to the rest of the laboratory (backfeed system). Design criteria, and features including simulation results are given.

An adaptive system for protecting a distribution network should determine and implement relay settings that are most appropriate for the prevailing state of the power system. This paper presents a technique for determining cbordinated relay settings. The technique uses the Simplex two-phase method; Phase I determines whether the constraints selected for illustrating the conditionality between primary and back up relays are feasible, and Phase II finds the optimal relay settings. A looped distribution system, protected by directional overcurrent relays, war; used for testing the technique. The tests were conducted in a laboratory environment: some results from those tests are reported in the paper.

The aim of this paper is to further study the rich vehicle routing problem (RVRP), which is a well-known combinatorial optimization problem arising in many transportation and logistics settings. This problem is known to be subject to a number of real life constraints, such as the number and capacity limitation of vehicles, time constraints including ready and due dates for each customer, heterogeneous vehicle fleets and different warehouses for vehicles. A Genetic Algorithm (GA)-based approach is proposed to tackle this highly constrained problem. The proposed approach efficiently resolves the problem despite its high complexity. To the best of our knowledge, no GA have been used for solving multi-depot heterogeneous limited fleet VRP with time windows so far. The new algorithm has been tested on benchmark and real-world instances. In fact, promising computational results have shown its good cost-effectiveness.

This paper describes recent work on the theoretical and algorithmic enhancements of the MIT method for steady state voltage monitoring and control. Under the conditions that no dynamic voltage problems are present, the method is intended primarily to monitor steady state voltage and reactive power conditions, to identify potential problem situations, and to make decisions regarding their severity. The developed method utilizes various reactive power resources on the system to remedy voltage violations. The corrective actions suggested are either in the order assigned by the operator or according to efficiency criteria, determined by this algorithm. The corrective actions ensure minimum possible voltage deviations from a given desired voltage profile. Corrective actiods are considered to be optimal in this sense. The method has the pnique feature of identifying minimum number of most effective corrective actions so that voltages are maintained within the given limits. The method does not solve the exact load flow equations, and therefore it avoids inversion of a full system size matrix. Reactive power scheduling is computed so that the resulting load voltages are within pre-specified target values. The computational time does not increase significantly with increase of system size, since no inversion of a system size matrix is needed. Numerical tests on a small and large scale electric power system (IEEE 39 & New England 1726) are presented and analyzed.

Power line communication (PLC) techniques seem a worthwhile research issue not only in civil applications, but also into the industrial scenario. The realisation of a communication network using the already existing electrical network is attractive for cost benefits, even though it represents a real challenge. Major problems concern communication reliability, effectiveness of transmission modulation methods and algorithms for error correction. EMC issues also must be taken into account, considering the consequences of injecting high-frequency harmonics into the AC power distribution system. This paper deals with the application of PLC techniques to the harsh and noisy environment of electrical drives. This study points out how the improvements in communication reliability can be achieved not only by a smart choice of the communication protocol, but also by using proper inverter modulation techniques, as Random Space Vector Modulation. The experimental results of transmission tests with both conventional and random space vector modulation techniques are here presented and discussed.

Resistance welders are a source of voltage fluctuations and flicker in industrial power distribution systems. The high-reactance welding transformer that limits the welding current creates a low-power-factor (pf) load. With hundreds of welders, factories may use synchronized welding cycles that lead to annoying flicker. Other facilities use random timing to prevent flicker, but suffer deep voltage sags due to simultaneous welding operations. Severe voltage variations reduce the power delivered to the welders, causing reduced heating and poor-quality welding joints. The paper examines the design and application of a mini-static var compensator (SVC) to improve the voltage quality on the welding circuits of industrial power distribution systems. The compact range of reactive-power demands for robotic welders suggest the use of thyristor-switched capacitors (TSCs). The compensation provides the necessary voltage control for consistent welds with the added benefit of reduced load currents throughout the industrial distribution system. The compensator control is coupled with the welder controls to mitigate the random reactive-power mismatches that are often seen with other SVC welding and arc-furnace applications.

Abstract—The introduction of generators in distribution grids, possibly together with storage systems, could cause a substantial change in grid operational practice: currently a rising idea proposes to treat generators and even loads as distributed resources that are able to supply services to the grid and accept on-line requests. To emphasise the advantages of Distributed Generation (DG) it is necessary to face the problem with a system approach. In this work both services coming from each generator and deriving from the co-ordination of ...

The consideration of distributed energy resources as non-wires alternatives for the elimination of overloads and voltage problems poses new challenges for their location and management. Traditional location methodologies approach the problem from the distribution system operator perspective, who tries to correct overload and voltage outside margins while minimizing other possible negative impacts in the network. The approach presented in this paper also considers the investor's point of view, seeking the most appropriate technology alternative, the maximum use of the available resource, and the minimum investment. Those aspects are explicitly taken into account in the formulation of the model, which takes the form of a mixed-integer nonlinear optimization problem. The proposed methodology is tested in two different scenarios using the medium-voltage distribution system benchmark of CIGRE. The results show that the interests of the distribution system operator and the investors can be jointly satisfied, achieving an effective, safe and realistic integration of new distributed resources. INDEX TERMS Distributed energy resources, distribution system operator, non-wires alternatives, renewable integration methods, optimal DER location, power systems. NOMENCLATURE SETS f k,t Active power flow through branch k in interval t (pu). q f k,t Reactive power flow through branch k in interval t (pu). z 1,2,3 Objective values. w d Installation cost for resource d (e). f d Use factor for resource d. i k,t Current magnitude squared through branch k in period t (pu). v i,t Voltage magnitude squared in bus i in period t (pu). u d Binary variable to indicate the installation of resource d.

An EMTP-based arc furnace model was developed for evaluation of flicker concerns associated with supplying a large integrated steel mill as they go from one to two furnace operation and as system changes are implemented that will affect the short circuit capacity at the 230 kV power supply substation. The model includes a dynamic arc representation which is designed to be characteristic of the initial portions of the melt cycle when the arc characteristics are the most variable (worst flicker conditions). The flicker calculations are verified using previous measurements with one furnace operation. Flicker simulations were then performed to evaluate a variety of different possible system strengths with both one and two furnaces in operation. The primary flicker measure used for this study is the unweighted rms value of the fluctuation envelope, expressed as a percentage of the rms line-to-ground voltage magnitude.

IEEE Recommended Practice 519 sets specific limits on harmonic voltages and currents at the "point of common coupling", which is usually interpreted as the revenue meter. Although most utilities will employ these limits simply to persuade and encourage their customers to reduce harmonics (and vice versa), it is also possible to construct economic incentives to encourage both the utility and the consumer to remain within the limits described in IEEE 519. This paper discusses seven approaches to this challenge, and discusses the advantages and disadvantages of each. It appears that the "Harmonic-Adjusted Power Factor " approach is pradical, justifiable, compatible with existing rate structures, and relatively easy to implement.

In modern society, the demand for electricity is ever-growing, making the minimization of power losses in distribution systems paramount. One significant aspect contributing to these losses is the strategic placement of capacitors within the distribution network. Efficient capacitor placement not only reduces power losses but also enhances the overall performance and reliability of the system. In today's world, where electricity is indispensable, minimizing power losses in the distribution system holds significant importance. This research introduces the Golden Jack Optimization (GJO) algorithm as a novel approach to address the challenge of capacitor placement in distribution systems. GJO, inspired by the foraging behavior of jackals, exhibits unique characteristics such as adaptability and efficiency in finding optimal solutions this paper proposes an innovative algorithm specifically designed for this purpose. To validate the effectiveness of the algorithm, extensive testing and experimentation have been conducted on the IEEE 69-bus system. This study aims to provide a practical and efficient solution to the challenge of power loss reduction within distribution systems. By harnessing the power of GJO and the insights gained from testing on the IEEE 69-bus system, we contribute to the ongoing efforts to enhance the efficiency and sustainability of electricity distribution networks. The results are compared with MPSO, TSM, GA-Fuzzy algorithms and proposed algorithm shows superior performance.

The local DC Power Distribution System of More Electric Aircraft is one of the cores of the electric power transmission. Because of some unidirectional devices (diode bridge and anti-run-back diodes), the system is not totally reversible. Some storage and dissipation systems are necessary to store or/and dissipate the returned energy to maintain the DC bus voltage and to increase the energy efficiency. This paper introduces four supervision strategies in two levels to maintain the DC bus voltage and compares these strategies with the help of two criteria: the voltage performance and efficiency.

The setting up process for support vector machines (SVM) is discussed in this paper. Such settings are normally obtained from exhaustive testing of SVM, settled on by using several configuration parameter values and evaluating performance by using techniques such as cross validation. The linear approach presented in this paper is based on redefining the classical SVM second-order objective function. Better setting parameters were obtained by using low computational cost methodology for resolving new linear optimisation. The proposed approach was applied to a typical classification problem regarding fault location in power distribution systems; the results so obtained were compared to those obtained using classical methodology. An 80% improvement was achieved in mean error when estimating fault location and 56% reduction in the computing time needed for obtaining the best results when using classical approaches.

The foreseeable shortages in conventional sources of electric power has increased the emphasis on the research and development of alternate sources of energy. In order to make a noteworthy impact, the alternate sources of energy need to be utility interactive by means of a power electronic interface (a dc to ac converter). The inherent assumption in the control of dc to ac converters is, that the dc voltage available at the input of the converter is constant. However, when the input is an unregulated dc source such as: a battery, fuel cell, photovoltaic cells or any other form of alternate source, maintenance of the constant dc voltage at the input of the converter is often impossible. A modified inverter switching technique is proposed for the interface with the utility grid such that the ac output of the inverter becomes immune to fluctuations in the unregulated input dc obtained from alternate energy sources. I. INTRODUCTION: The threatened limitations on conventional sources of electric power, posed by future shortages of fossil and nuclear fission fuels and the reduced availability of Iiydroelectric power sites, has focused attention on "unconventional" sources or "alternate" sources of electric power. Renewable and nonpolluting sources of energy such as sun and wind have an enormous potential to supplement the fossil and nuclear based generation of electricity. Also, there has been 96 WM 043-0 EC A paper recommended and approved by the IEEE Energy Development and Power Generation Committee of the IEEE Power Engineering Society for presentation at the 1996 IEEEPES Winter Meeting,