919 research outputs found
Voltage quality monitoring, dips classification and responsibility sharing
No full textCEER and EURELECTRIC cooperation in the field
of quality of electricity supply, involving joint meetings and the
participation at the relevant CENELEC Technical Committee,
contributed to the results attained in the recent publication of the
EN 50160:2010 edition that includes a new voltage dips
classification table allowing harmonisation at European level on
voltage dips data collection. The generalisation of voltage quality
monitoring data publication all over Europe will allow the
definition of responsibility sharing between the different involved
stakeholders and the evolution of voltage quality regulation
applied at national level. Examples from Sweden and Italy are
briefly presented in this paper
Understanding power quality problems voltage sags and interruptions
No full text"Power quality problems have increasingly become a substantial concern over the last decade, but surprisingly few analytical techniques have been developed to overcome these disturbances in system-equipment interactions. Now in this comprehensive book, power engineers and students can find the theoretical background necessary for understanding how to analyze, predict, and mitigate the two most severe power disturbances: voltage sags and interruptions. This is the first book to offer in-depth analysis of voltage sags and interruptions and to show how to apply mathematical techniques for practical solutions to these disturbances. From UNDERSTANDING AND SOLVING POWER QUALITY PROBLEMS you will gain important insights into . Various types of power quality phenomena and power quality standards. Current methods for power system reliability evaluation. Origins of voltage sags and interruptions. Essential analysis of voltage sags for characterization and prediction of equipment behavior and stochastic prediction. Mitigation methods against voltage sags and interruptions" An Instructor Support FTP site is available from the Wiley editorial department: ftp://ftp.ieee.org/uploads/press/bollen Sponsored by: IEEE Power Electronics Society, IEEE Industry Applications Society, IEEE Power Engineering Societ
Power quality in the future grid - Results from CIGRE/CIRED JWG C4.24
No full textThis paper gives a status report on activities of CIGRE/CIRED JWG C4.24. The following issues are addressed in the paper: Introduction, scope of the report and terminology; New developments in power electronics (PE); Changes in probability of interference; Microgrids and PQ; Volt-VAR control and PQ; Feeder reconfiguration and PQ; Demand side management and PQ; New measurement techniques; New mitigation
An unsupervised learning schema for seeking patterns in rms voltage variations at the sub-10-minute time scale
No full textThis paper proposes an unsupervised learning schema for seeking the patterns in rms voltage variations at the time scale between 1 s and 10 min, a rarely considered time scale in studies but could be relevant for incorrect operation of end-user equipment. The proposed framework employs a Kernel Principal Component Analysis (KPCA) followed by a k-means clustering. The schema is applied on 10-min time series with a 1-s time resolution obtained from 44 different periods of a location south of Sweden. Then, ten patterns are obtained by reconstructing the 10-min time series from each cluster center. The results of the proposed schema show a good separation of cluster centers. Moreover, some statistical power-quality indices are applied to the whole dataset, showing voltage variation between (0.5–3) V over a 10-min window. Obtaining the most suitable indices and applying them to the ten obtained cluster centers and their belonging time series shows that the existing statistical indices may not be enough to show a complete picture of the sub-10 min actual variations. This outcome shows the necessity of extracting 10-min patterns through our proposed schema besides the existing statistics to quantify the voltage variations, levels, and patterns together. Findings of this paper are: Not forgetting the sub-10-min time scale; The necessity of employing both statistics and the proposed schema; Extraction of ten typical patterns; The need for the statistics and patterns that are justified as changes in equipment connected to the grid; and compressing a huge amount of data from power-quality monitoring. The proposed schema is applied to a much less understood phenomena/disturbance type so that this work will result in general knowledge beyond the specific case study
The Smart Grid: Adapting the Power System to New Challenges
No full textThis book links the challenges to which the electricity network is exposed with the range of new technology, methodologies and market mechanisms known under the name "smart grid." The main challenges will be described by the way in which they impact the electricity network: the introduction of renewable electricity production, energy efficiency, the introduction and further opening of the electricity market, increasing demands for reliability and voltage quality, and the growing need for more transport capacity in the grid. Three fundamentally different types of solutions are distinguished in this book: solutions only involving the electricity network (like HVDC and active distribution networks), solutions including the network users but under the control of the network operator (like requirements on production units and curtailment), and fully market-driven solutions (like demand response). An overview is given of the various solutions to the challenges that are possible with new technology; this includes some that are actively discussed elsewhere and others that are somewhat forgotten.Linking the different solutions with the needs of the electricity network, in the light of the various challenges, is a recurring theme in this book.</p
Consequences of smart grids for power quality: Overview of the results from CIGRE joint working group C4.24/CIRED
No full textThis paper gives an overview of the expected unintended (negative) consequences for power quality of several on-going developments in the power system. Four developments directly related to smart-grid technology are covered: microgrids; advanced voltage control; feeder reconfiguration; and demand-side management. Four developments indirectly related are also covered: new sources of electricity production; increased used of active power-electronic converters; shift from overhead lines to cables; and new types of lighting. The paper summarizes the discussions in an international working group and presents the main findings are recommendations
A new joint sliding-window ESPRIT and DFT scheme for waveform distortion assessment in power systems
No full textThis paper proposes a novel scheme that jointly employs a sliding-window ESPRIT and DFT for estimating harmonic and interharmonic components in power system disturbance data. In the proposed scheme, separate stages are utilized to estimate the voltage fundamental component, harmonics and interharmonics. This includes the estimation of the fundamental component from lowpass filtered data using a sliding-window ESPRIT, of harmonics from a sliding-window DFT with a synchronized window, and of interharmonics from the residuals by applying the sliding-window ESPRIT. Main advantages of the approach include high resolution and accuracy in parameter estimation and significantly reduced computational cost. Experiments and comparisons are made on both synthetic and measurement data. Results have shown the effectiveness and efficiency of the proposed scheme
Volt-var control and power quality
No full textThis paper summarizes the state of discussions in CIGRE/CIRED joined working group C4.24, concerning expected impacts on the power quality of future methods for volt-var-control in the distribution grid. The positive impacts include the reduction of the number of overvoltage and undervoltages and also a reduction of voltage unbalance, when some control schemes are applied. Potential negative impacts include an increased number of short-duration undervoltages, rapid voltage changes, flicker, and voltage transients; a higher risk of harmonic resonances; and increased emission of supraharmonics. All these potential impacts are discussed in the paper
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