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The fast developments in power electronic technology have made it possible to mitigate voltage disturbances in power system. Among the voltage disturbances challenging the industry, the voltage sags are considered the most important problem to the sensitive loads. Dynamic voltage restorer (DVR) is a series connected power electronic based device that can quickly mitigate the voltage sags in the system...
This paper is dedicated to the research on the digital analysis system of the power quality which is greatly deteriorated by the development of power electronic technology and the widespread application of nonlinear loads. Researchers at home and abroad have done many studies on the measurement of the power quality indicators and have proposed many measuring methods which are too complex to be used...
In this paper sensorless control method fora an Active Front End (AFE) converter is presented. Developed algorithm is based on Voltage Oriented Control (VOC), extended by additional Voltage Dips Compensation (VDC) module. Moreover improved Virtual Flux (VF) estimator based on SOGI-QSG for LCL filter has been shown. This new sensorless control method can assure sinusoidal and balanced grid currents...
Quantification of the flicker generated by wind turbines is a rather complex process requiring high-precision measurements. Based on the measurements of voltage and current time-series, the procedure uses an inductive circuit model to make the final measurements site-independent. This paper presents a study on the inaccuracy introduced by the numerical algorithms in calculating the derivative of the...
IEEE Std 1564-2014 Guide for Voltage Sag Indices is a new standard that identifies appropriate voltage sag indices and characteristics of electrical power and supply systems as well as the methods for their calculation. This paper presents an overview of IEEE 1564, which was approved as a new standard by IEEE RevCom in March 2014. The paper summarizes the IEEE 1564 methods for quantifying the severity...
This paper presents a new method for relative location of voltage sags and capacitor switching transients based on voltage measurements only. Voltage sags caused by network faults and transients caused by bank capacitor energizing are considered in this work. The algorithm automatically operates for assessing power quality, characterising and extracting information from voltage records obtained from...
Electric arc furnace and its influence in the power system are studied in this paper. Two models that allow to evaluate its behavior during steady state are shown. These models has different complexity level; the first model takes into account the main nonlinearities of the load; the other assumes that current-voltage characteristic in the arc is piece-wise linear. Electromagnetic transients program...
This paper presents a case study of voltage sags on a utility and industrial co-generation system interconnection. The system was simulated through a Real Time Digital Simulator (RTDS) and a new voltage sag source locator is evaluated. This new approach is capable of locating voltage sags source based on power flow behavior. The proposed algorithm calculates the positive, negative, and zero sequence...
With the growing number and capacity of photovoltaic installations connected to distribution networks, power quality issues related to voltage regulation, are becoming relevant problems for power distribution companies and for PV owners. In this context, the paper investigates on unintentional disconnection of photovoltaic plants connected to weak low voltage distribution network. Measurement results...
This paper aims to evaluate the performance of commercial power quality meters. By using a high precision programmable voltage and current source, several meters are analyzed and compared. At first, At first, distorted three-phase voltage signals are applied to several kinds of PQ instruments, considering harmonics, sags, swells, as well as unbalanced voltages. Next, the features of these events are...
Lately, in operation of power system installation have found numerous perturbations affecting the normal functioning of connected users, mainly at 110 kV network, in vicinity of large disturbing users. The monitoring of power quality within the network nodes, which are connected directly disturbing users to the transmission network, allowed to know how specific the requirements on power quality and...
This paper is a continuation of Part I [1] and presents the application of a comprehensive system of registration, archiving and data processing for the wide-area monitoring of power quality in a separated part of real power grid with distributed renewable generation. Real case studies related to tracking of disturbances' wandering and localization of sources of voltage disturbances are presented.
Nowadays, the ITIC curve is commonly used for evaluating voltage dips' severity. However, this curve may not catch equipment sensitivity well enough and it certainly lacks the information about the probability of whether any equipment is indeed switched on or not. In this paper we present a novel voltage dip severity evaluation method based on the lost voltage-time area of the dip and also give detailed...
This paper presents a comparative study of the method used for measuring the flicker emission from wind turbines as currently defined in standard IEC 61400-21 and the new proposal included in the draft version of the revised standard. The new procedure applies a different arrangement scheme to the flicker measurements, and simplifies the statistical analysis to obtain the final flicker coefficients...
This paper highlights the shortfalls, existing in the methods, currently used for the characterization of voltage sags, from recorded waveforms. Test waveform, available with IEEE data base, and data generated from Matlab® simulations, are used to reveal their ambiguities. It is found that none of the existing methods give accurate and complete characteristics of the voltage sag event. Still large...
This paper solves problematic of supply voltage dips and their influence to modern electric drive (i.e. induction machine supplied from indirect frequency converter). The paper presents the control algorithms for basic variant the most used drives (with non-controlled rectifier and without additional converter) and variants with more complicated power circuits (with active rectifier respectively with...
The introduction of electric vehicles in currently urban transportation system becomes tendency and attractive alternation to traditional fuel cars. Electric vehicles include certain different types and are powered through electric vehicle chargers which are elements in an infrastructure that supplies electric energy for the recharging of the plug-in electric vehicles. There has been much more concern...
The present paper deals with the case study of an existing ac arc furnace facility. A field measuring campaign was carried out for an industrial consumer. One of the many aspects of power quality that can affect electricity users is voltage fluctuation that causes lights to flicker. The main power quality indices regarding flicker levels are reported in the paper with reference to the current standards.
This paper introduces a new algorithm of polyphasic segmentation. This new algorithm combines the strength of the concept of voltage signal tensor with the benefits offered by the residual segmentation technique in order to generate a unique pattern of segmentation. This segmentation strategy is validated using a set of synthetic signals with voltage variation in the remnant voltage and the start...
Power Quality assessment is based on measuring and monitoring of specific parameters. Measure uncertainty level is important because parameters values are estimated based on this information and then compared with admissible limits. More, the decisions and solutions for electromagnetic pollution limitation is also based on that results. ISO/IEC 61000-4-30:2008 Standard contains uncertainty levels...
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