scholarly journals Cluster-Based Method to Determine Base Values for Short-Term Voltage Variation Indices

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 149
Author(s):  
Paulo Vitor Grillo de Souza ◽  
José Maria de Carvalho Filho ◽  
Daniel Furtado Ferreira ◽  
Jacques Miranda Filho ◽  
Homero Krauss Ribeiro Filho ◽  
...  
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Real Data ◽  
Regulatory Agencies ◽  
Voltage Sag ◽  
Short Term ◽  
Voltage Variation ◽  
Adequate Definition ◽  
Definition Of ◽  
Electricity Utility

This paper proposes a methodology for establishing base values for short-term voltage variation indices. The work is focused on determining which variables best describe the disturbance and based on that, establish clusters that allow a more adequate definition of base values for the indices. To test the proposed methodology, real data from 19 distribution systems belonging to a Brazilian electricity utility were used and consequently the index presented in the country standard was considered. This study presents a general methodology that can be applied to all distribution systems in Brazil and could serve as a guide for the regulatory agencies in other countries, to establish base values for their indices. Furthermore, the objective is to show through the results that, with the database used is possible to establish clusters of distribution systems related to the voltage sag and with these establish a base impact factor, distinct for each distribution system.

scholarly journals When is a Learning Object not an Object: A first step towards a theory of learning objects

2002 ◽  
Vol 3 (2) ◽  
Author(s):  
Mike Sosteric ◽  
Susan Hesemeier
Keyword(s):  
Economies Of Scale ◽  
Learning Objects ◽  
Short Term ◽  
Object A ◽  
Smart Learning ◽  
Smart Learning Environments ◽  
Adequate Definition ◽  
Definition Of ◽  
Conceptual Confusion

<p> For some, “learning objects" are the “next big thing” in distance education promising smart learning environments, fantastic economies of scale, and the power to tap into expanding educational markets. While learning objects may be revolutionary in the long term, in the short term, definitional problems and conceptual confusion undermine our ability to understand and critically evaluate the emerging field. This article is an attempt to provide an adequate definition of learning objects by (a) jettisoning useless theoretical links hitherto invoked to theorize learning objects, and (b) reducing the definition of learning objects to the bare essentials. The article closes with suggestions for further research and further refinement of the definition of learning objects. </P>

Impacts of Distributed Generators on Voltage Sag Analysis

2013 ◽  
Vol 732-733 ◽  
pp. 877-881
Author(s):  
Jenjira Boonnamol ◽  
Thavatchai Tayjasanant
Keyword(s):  
Particle Swarm Optimization ◽  
Optimization Algorithm ◽  
Distribution System ◽  
Distribution Systems ◽  
Particle Swarm Optimization Algorithm ◽  
Test System ◽  
Voltage Sag ◽  
Swarm Optimization ◽  
Distributed Generators ◽  
Three Phase

This paper presents impacts of distributed generators (DGs) such as synchronous-based DG and inverter-based DG on voltage sag analysis in distribution systems. Voltage sag analysis is assessed through area of vulnerability (AOV), number of sags frequency (NSF) and voltage sag index (SARFI). Single line-to-ground and three-phase faults are investigated. Size and location of DG are carried out by using Particle Swarm Optimization algorithm (PSO) in order to minimize losses and number of sag frequency. Roy Billinton Test System (RBTS) Bus 2 is used for simulation cases. Results show that the distribution system with DG installed improves voltage sag performance compared with the system without DG installed.

Minimization of Financial Losses due to Voltage Sag in an Indian Distribution System using D-STATCOM

2009 ◽  
Vol 10 (3) ◽  
Author(s):  
Arup Kumar Goswami ◽  
Chandra Prakash Gupta ◽  
Girish Kumar Singh
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Short Circuit ◽  
Cost Benefit ◽  
Voltage Sag ◽  
Fault Calculation ◽  
Real Distribution ◽  
Uninterruptible Power ◽  
The Cost ◽  
Financial Losses

Voltage sag can cause considerable financial damage in an industry containing sensitive equipment. Many solutions exist to minimize financial losses due to voltage sag, varying from modification within the process itself to restructuring the supplying grid. In many cases the only possibility to minimize the financial losses is to install mitigation devices between the grid and the sensitive process such as power electronics devices Uninterruptible Power Supply (UPS). However, protecting the entire process by a dynamic or static UPS often turns out to be too expensive. This paper presents the minimization of financial losses due to voltage sag produced by balanced and unbalanced short circuit that occur at distribution system bus and along the transmission line using system impedance matrix (Z Bus) which incorporates D-STATCOM. The overall financial losses due to voltage sag could significantly change depending on the location of D-STATCOM used. In order to have an assessment of financial losses in real distribution systems, the classical static fault calculation should be amended to incorporate the effect of installation of these devices on financial losses. The cost-benefit analyses of inducting D-STATCOM for mitigating the effects of voltage sags have also been performed.Case studies based on a real Indian distribution system are used to illustrate the modeling method and the effectiveness of these devices in voltage sag mitigation.

scholarly journals Dynamic Hydraulics in a Drinking Water Distribution System Influence Suspended Particles and Turbidity, But Not Microbiology

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 109
Author(s):  
Emmanuelle I. Prest ◽  
Peter G. Schaap ◽  
Michael D. Besmer ◽  
Frederik Hammes
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Age ◽  
Short Term ◽  
Drinking Water Distribution Systems ◽  
Hydraulic Conditions ◽  
Drinking Water Distribution ◽  
Particle Counts

Spatial and short-term temporal changes in water quality as a result of water age and fluctuating hydraulic conditions were investigated in a drinking water distribution system. Online measurements of total and intracellular adenosine tri-phosphate (ATP), total and intact cell concentrations measured with flow cytometry (FCM), turbidity, and particle counts were performed over five weeks at five subsequent locations of the distribution system. The high number of parallel FCM and ATP measurements revealed the combined effect of water age and final disinfection on spatial changes in microbiology in the system. The results underlined that regular daily dynamics in flow velocities are normal and inevitable in drinking water distribution systems, and significantly impact particle counts and turbidity. However, hydraulic conditions had no detectable impact on the concentration of suspended microbial cells. A weak correlation between flow velocity and ATP concentrations suggests incidental resuspension of particle-bound bacteria, presumably caused by either biofilm detachment or resuspension from sediment when flow velocities increase. The highly dynamic hydraulic conditions highlight the value of online monitoring tools for the meaningful description of short-term dynamics (day-scale) in drinking water distribution systems.

scholarly journals Analysis of voltage sag compensation in distribution systems using a multilevel DSTATCOM in ATP/EMTP

DYNA ◽  
2015 ◽  
Vol 82 (192) ◽  
pp. 26-36
Author(s):  
Herbert Enrique Rojas-Cubides ◽  
Audrey Soley Cruz-Bernal ◽  
Harvey David Rojas-Cubides
Keyword(s):  
Power Quality ◽  
Distribution System ◽  
Distribution Systems ◽  
Reactive Power ◽  
Test System ◽  
Voltage Sag ◽  
Voltage Sags ◽  
Random Generation ◽  
Power Quality Disturbances ◽  
Static Compensator

<p class="Abstract"><span lang="EN-US">Voltage sags are the most common power quality disturbances in electrical facilities. It may cause malfunction in sensitive equipment and process interruption. The distribution static compensator (DSTATCOM) is a device that can compensate voltage sags by injecting reactive power into distribution system. This paper shows the influence on voltage sags characteristics by the presence of twelve-pulse DSTATCOM in the modified IEEE-13 distribution system. The analysis is performed by means of a random generation of disturbances using a MATLAB routine to identify the critical buses of the test system. Further, the DSTATCOM model taking advantage of the available elements from ATP/EMTP software is described. Simulations show that when DSTATCOM is placed directly to affected bus it is possible to obtain a complete mitigation of the voltage sag. Finally, the relation between the reactive power injected by DSTATCOM, the type of voltage sag and the location of affected bus is considered.</span></p>

scholarly journals A Novel Analysis of Improving Displacement Factor Using IVDFC in Distribution Systems

2017 ◽  
Vol 6 (3) ◽  
pp. 193
Author(s):  
M. Padmarasan ◽  
C.T. Manikandan ◽  
N. Karthikeyan ◽  
L. Jayaprakash ◽  
C.S. Ajin Sekhar
Keyword(s):  
Critical Load ◽  
Distribution System ◽  
Distribution Systems ◽  
Reactive Power ◽  
Voltage Sag ◽  
Dynamic Voltage Restorer ◽  
Power Exchange ◽  
Voltage Restorer ◽  
Dynamic Voltage ◽  
Displacement Factor

In this paper discuss the new approach for improving displacement factor using an Interline Dynamic Voltage Restoring and Displacement Factor Controlling Device (IVDFC) in a distribution system. An Interline Dynamic Voltage Restorer (IDVR) is perpetually engaged in distribution systems to mitigate voltage sag/swell problems. An IDVR simply consists of numerous dynamic voltage restorers (DVRs) sharing a common dc link connecting independent feeders to safe electric power to critical loads. The IDVR is operated that it hold the voltage across the critical load bus terminals constant at system nominal frequency irrespective of the changes occurring in source voltages frequency. While one of the DVRs compensates for the local voltage sag in its feeder, the other DVRs reload the common dc-link voltage. For normal voltage levels, the DVRs should be bypassed. Instead of bypassing the DVRs in normal conditions, this paper proposes operating the DVRs, if needed, to improve the displacement factor (DF) of one of the involved feeders. DF improvement can be achieved via active and reactive power exchange (PQ sharing) between different feeders. To successfully apply this concept, several constraints are addressed throughout the paper. The simulation model for this system is developed using MATLAB which is shown that the voltage across the critical load is regulated completely.

scholarly journals Enhancement of voltage regulation using a 7-Level inverter based electric spring with reduced number of switches

2020 ◽  
Vol 11 (2) ◽  
pp. 555
Author(s):  
K. K. Deepika ◽  
J. Vijaya Kumar ◽  
G. Kesava Rao
Keyword(s):  
Critical Load ◽  
Distribution System ◽  
Distribution Systems ◽  
Voltage Regulation ◽  
Voltage Sag ◽  
Demand Side ◽  
Line Voltage ◽  
Load Voltage ◽  
Voltage Balance ◽  
Switched Capacitor Converter

Electric Springs has been testified recently to enhance voltage regulation in distribution systems using demand side management. In this paper, a 7-level Multilevel Inverter (MLI) with a resonant switched capacitor Converter based on sinusoidal PWM, is implemented to analyze the performance of an electric spring under voltage variations at PCC. By the proposed MLI based ES, voltage regulation of critical load voltage is studied for voltage sag and swell conditions. Remarkable features of the proposed topology are maintaining voltage balance in input capacitors and reduction of power components. Simulations have been done in MATLAB/Simulink on distribution system with DGs equipped with MLI based ES under line voltage anomalies. Tested results are analyzed with THD% in critical load voltage.

scholarly journals Research and Control of STATCOM using ANN and ANFIS

2019 ◽  
Vol 8 (2S11) ◽  
pp. 4172-4181
Keyword(s):  
Power Quality ◽  
Distribution System ◽  
Distribution Systems ◽  
Fuzzy Controller ◽  
Voltage Sag ◽  
Power Electronic ◽  
Active Power Filters ◽  
Wide Range ◽  
In Series ◽  
Power Application

Power quality issues are of great concern in transmission and distribution system now a day due to the sensitive nature of the loads. The sensitive nature of the load increases with the advent of power electronic technology. It has become important, particularly, with the introduction of sophisticated devices, whose performance is very sensitive to the quality of power supply that results in a failure of end use equipment. In distribution systems voltage sag are more prominent. Power quality problems cannot be eliminated by using conventional filters. Therefore power electronic based Active Power Filters (APF) are most commonly used now a days. Voltage sag problems are the most frequently occurring and detrimental power quality problems. At present, a wide range of very flexible controllers, are emerging for custom power application to correcting the voltage sag in a distributed system. Among these controllers STATCOM are most effective devices, along with controlling methodology Mamdani Fuzzy Controller (MFC), ANN and ANFIS controllers. A STATCOM inject the voltage in series with the system voltage and a STATCOM injects a current into the system to correct the voltage sag. In their existing system they should be performance of STATCOM using PI controller showed to be better performance for solving voltage sag problem. But we are going to propose the ANN and ANFIS on STATCOM in order to increase the efficiency and their better performance to rectify the power quality problems.

scholarly journals Short-Term Analysis of Distribution Systems with Wind Farms Using Multi Resolution Analysis Neural Networks

2012 ◽  
Vol 128 (1) ◽  
pp. 11-20
Author(s):  
Meisam Pourahmadi-Nakhli ◽  
Ali Reza Seifi
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Distribution System ◽  
Distribution Systems ◽  
Load Flow ◽  
Analysis Tool ◽  
System State ◽  
State Variables ◽  
Short Term ◽  
Power Distribution System

Abstract Since wind power generation as a major input of the power distribution system strictly relies on wind speed, stochastic wind fluctuations challenge an accurate prediction of the power generation. In this paper, an enhancement on Artificial Neural Network-based predicting model has been used to predict the major input of the system. The correlation between a smooth-dilated wavelet and wind speed samples has been calculated to decompose wind series into resolutions in which there is more regular patterns to be approximated. This predicting scheme was validated on the real wind (generation) data as well as consumption level of a real system to give a short-term prediction of the system inputs. The unbalanced three-phase load flow as a robust analysis tool determines system state variables under these predicted inputs. The results indicate the high accuracy of the method in predicting the system state variables from 3 hours to a day in advance.

scholarly journals Enhancing power quality of ANN controller based PhotoVoltaic source injected DVR

2018 ◽  
Vol 7 (2.31) ◽  
pp. 155
Author(s):  
T Ramesh ◽  
S K. Mayurinathan ◽  
R Saravanan ◽  
G Emayavaramban
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Control Method ◽  
Voltage Sag ◽  
Voltage Waveform ◽  
High Quality ◽  
Load Voltage ◽  
On Line ◽  
Stable Voltage

The DVR is a series connected FACTS controller used to compensate voltage disturbance in distribution systems. The main purpose of  the DVR is to examine the load voltage waveform regularly if any disorder happens, the equilibrium or excess voltage is injected to the load voltage. The most important advantage of the DVR is observance the users all the time on-line with high quality stable voltage maintaining the permanence of production.  In this dissertation, a Photovoltaic voltage injected with an ANN control method for DVR that protects a sensitive load, to counter voltage sag under uneven loading conditions (linear, non-linear) is presented. DVR along with other parts of the distribution system are simulated using MATLAB/ SIMULINK.  

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