Artykuły w czasopismach: „PQ PROBLEMS”

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Öhnell, Richard F. "Some PQ problems". Acta Medica Scandinavica 130, S206 (24.04.2009): 17–19. http://dx.doi.org/10.1111/j.0954-6820.1948.tb12015.x.

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Arov, D. Z., B. Fritzsche i B. Kirstein. "Completion problems forj pq-inner functions. II". Integral Equations and Operator Theory 16, nr 4 (grudzień 1993): 453–95. http://dx.doi.org/10.1007/bf01205289.

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Arov, D. Z., B. Fritzsche i B. Kirstein. "Completion problems forj pq-inner functions. I." Integral Equations and Operator Theory 16, nr 2 (czerwiec 1993): 155–85. http://dx.doi.org/10.1007/bf01358952.

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Bjerring, Jens Christian, i Wolfgang Schwarz. "Granularity Problems". Philosophical Quarterly 67, nr 266 (4.04.2016): 22–37. http://dx.doi.org/10.1093/pq/pqw028.

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Goud, B. Srikanth, Ch Rami Reddy, Mohit Bajaj, Ehab E. Elattar i Salah Kamel. "Power Quality Improvement Using Distributed Power Flow Controller with BWO-Based FOPID Controller". Sustainability 13, nr 20 (11.10.2021): 11194. http://dx.doi.org/10.3390/su132011194.

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The integration of hybrid renewable energy sources (HRESs) into the grid is currently being encouraged to meet the increasing demand for electric power and reduce fossil fuels which are causing environmental-related problems. Integration of HRESs into the grid can create some power quality (PQ) problems. To mitigate PQ problems and improve the performance of grid-connected HRESs some flexible devices should be used. This paper presents a distributed power flow controller (DPFC), as a type of flexible device to mitigate some PQ problems, including voltage sag, swell, disruptions, and eliminating the harmonics in a hybrid power system (HPS). The HPS presented in this work comprises a photo voltaic (PV) system, wind turbine (WT) and battery energy storage system (BESS). As a result, black widow optimization (BWO) with DPFC with real and reactive power (DPFC-PQ) is built in this paper to solve the PQ issues in HRES systems. The main aim of the work is to mitigate PQ problems and compensate for load demand in the HRES scheme. The controller used to drive this DPFC-PQ is a fractional-order PID (FOPID) controller optimized by the black widow optimization (BWO) technique. To assess the capability of BWO in fine-tuning the FOPID controller parameters, twelve optimization techniques were presented: P&O, PSO, Cuckoo, GA, GSA, BBO, Whale, ESA, RFA, ASO, and EVORFA. Additionally, a comparison between the FOPID controller and the classical PI controller is introduced. The results showed that the proposed BWO-FOPID controller for DFPC had mitigated the PQ problems in grid-connected HRESs. The system’s performance with the presented BWO-FOPID controller is compared with eleven optimization techniques used to optimize the FOPID controller and also compared with the conventional PI controller. The design of the proposed system is implemented in the MATLAB/Simulink platform and performances were analyzed.

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Bhende, C. N., A. Kalam i S. G. Malla. "Mitigation of Power Quality Problems in Grid-Interactive Distributed Generation System". International Journal of Emerging Electric Power Systems 17, nr 2 (1.04.2016): 165–72. http://dx.doi.org/10.1515/ijeeps-2015-0163.

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Abstract Having an inter-tie between low/medium voltage grid and distributed generation (DG), both exposes to power quality (PQ) problems created by each other. This paper addresses various PQ problems arise due to integration of DG with grid. The major PQ problems are due to unbalanced and non-linear load connected at DG, unbalanced voltage variations on transmission line and unbalanced grid voltages which severely affect the performance of the system. To mitigate the above mentioned PQ problems, a novel integrated control of distribution static shunt compensator (DSTATCOM) is presented in this paper. DSTATCOM control helps in reducing the unbalance factor of PCC voltage. It also eliminates harmonics from line currents and makes them balanced. Moreover, DSTATCOM supplies the reactive power required by the load locally and hence, grid need not to supply the reactive power. To show the efficacy of the proposed controller, several operating conditions are considered and verified through simulation using MATLAB/SIMULINK.

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Karthik, N., Shaik Abdul Gafoor i M. Surya Kalavathi. "Classification of Power Quality Problems by Wavelet Fuzzy Expert System". Advanced Materials Research 463-464 (luty 2012): 1573–78. http://dx.doi.org/10.4028/www.scientific.net/amr.463-464.1573.

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Electric power quality, which is a current interest to several power utilities all over the world, is often severely affected by harmonics and transient disturbances. There is no unique model which can assess the power quality problem and to identify and classify them properly. Existing automatic recognition methods need improvement in terms of their versatility, reliability, and accuracy. The FUZZY LOGIC based tools have been applied for the PQ classification. This paper addresses Power quality problem classification by wavelet and fuzzy expert system. Major Key issues and challenges related to these advanced techniques in automatic classification of PQ problems are highlighted. New intelligent system technologies using DSP, expert systems, AI and machine learning provide some unique advantages in intelligent classification of PQ distortions

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Dhanakodi.V, N.Balachandar i M.Gayathri. "Power Quality Monitoring and Feedback Control for Hybrid Renewal Energy System using Meta Heuristic Optimization Technique". International Journal of Scientific Methods in Intelligence Engineering Networks 01, nr 04 (2023): 33–44. http://dx.doi.org/10.58599/ijsmien.2023.1404.

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Solar and wind energy are becoming more popular. Hybrid Renewable Energy System (HRES) is a fast-growing power industry segment. Power quality (PQ) issues have increased as renewable energy has increased in the electricity supply. This study will help electrical engineers identify power quality (PQ) disruptions from hybrid renewable power sources like solar and wind. The investigation will predict powergeneration-induced PQ problems. A self-contained Hybrid Renewable Energy System (HRES) is the project’s main goal. We will collect and analyses energy system data using Grey Wolf Optimization to improve mitigation and reduce PQ interruptions. The suggested technique analyses live data from several sources and historical data in many formats. To prevent problems, the hardware’s controllers will receive the data. Algorithms and designers will improve system efficiency and design ability. The monitoring system will predict PQ disturbances caused by electricity generation from different energy sources. The suggested device labels PQ disturbances by impact.

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Mewes, Ricarda, Boris Friele i Evert Bloemen. "Validation of the Protect Questionnaire: A tool to detect mental health problems in asylum seekers by non-health professionals". Torture Journal 28, nr 2 (28.07.2018): 56–71. http://dx.doi.org/10.7146/torture.v28i2.106884.

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Introduction: Prevalence rates of trauma-related mental disorders such as posttraumatic stress disorder (PTSD) or major depression (MD) are high in asylum seekers. The PROTECT Questionnaire (PQ) was designed to detect indications of those disorders in asylum seekers. Empirical data are needed to evaluate the PQ psychometrically. The objective of this study is to investigate the reliability, validity, sensitivity, and specificity of the PQ. Method: The PQ and validated questionnaires for PTSD (Posttraumatic Diagnostic Scale, PDS) and depression (Patient Health Questionnaire-9, PHQ- 9) were filled in by a sample of recently arrived asylum seekers in Germany (n=141). A sub-sample of 91 asylum seekers took part in a structured clinical interview to diagnose PTSD or MD (SCID-I). Results: The PQ showed a one-factor structure and good reliability (Cronbach’s ⍺= .82). It correlated highly with the PDS and the PHQ-9 (rs=.53-.77; ps≤.001). Diagnostic accuracy with regard to PTSD (AUC=.74; SE=.06; p<.001; 95%-CI=.63-.84) and MD (AUC=.72; SE=.06; p<.001; 95%-CI=.61- .83) was adequate, suggesting an optimal cut-off of 8 or 9. By categorizing participants into a low- and high-risk category, the PQ differentiated well between asylum seekers who fulfilled a PTSD or MD diagnosis and those who did not. Discussion: The results support the use of the PQ as a reliable and valid instrument for the purpose of detecting signs and symptoms of the two most common mental disorders in asylum seekers. Persons found to be at risk of mental disorders should be referred to a clinical diagnostic procedure.

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Jiang, Shulun, Jian Yang i Di-an Fang. "Transcriptome changes of Takifugu obscurus liver after acute exposure to the oxygenated-PAH 9,10-phenanthrenequione". Physiological Genomics 52, nr 8 (1.08.2020): 305–13. http://dx.doi.org/10.1152/physiolgenomics.00022.2020.

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Contamination with polycyclic aromatic hydrocarbons (PAHs) causes noticeable ecological problems in aquatic ecosystems. 9,10-Phenanthrenequione (9,10-PQ) is an oxidized PAH and is highly toxic to aquatic animals. However, the effects of 9,10-PQ on the molecular metabolism of fish remain largely unknown. In this study, Takifugu obscurus juveniles were acutely exposed to 44.30 µg/L 9,10-PQ for 3 days. The transcriptome profile changes in their livers were compared between the 9,10-PQ treatment group and the control using T. rubripes as the reference genome. The results identified 22,414 genes in our transcriptome. Among them, 767 genes were differentially expressed after exposure to 9,10-PQ, which enriched 16 KEGG pathways. Among them, the glycolysis, phagosome, and FOXO signaling pathways were significantly activated in 9,10-PQ treatment compared with the control. These data indicate that 9,10-PQ increased the glycolysis capacity to produce more energy for resistance and harmed immune function. Moreover, several genes related to tumorigenesis were significantly upregulated in response to 9,10-PQ, displaying the carcinogenic toxicity of 9,10-PQ to T. obscurus. Genes in steroid biosynthesis pathways were downregulated in the 9,10-PQ treatment group, suggesting interference with the endocrine system. Overall, these findings provide information to help evaluate the environmental risks that oxygenated-PAHs present to T. obscurus.

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Bläsius, Thomas, i Ignaz Rutter. "Simultaneous PQ-Ordering with Applications to Constrained Embedding Problems". ACM Transactions on Algorithms 12, nr 2 (12.02.2016): 1–46. http://dx.doi.org/10.1145/2738054.

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MANIMALA, K., K. SELVI i R. AHILA. "POWER DISTURBANCES PATTERN RECOGNITION USING SUPPORT VECTOR MACHINE". International Journal of Information Acquisition 08, nr 01 (marzec 2011): 53–64. http://dx.doi.org/10.1142/s0219878911002331.

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Recently, many signal processing techniques, such as fast Fourier transform, short-time Fourier transform, wavelet transform (WT), and wavelet packet transform (WPT), have been applied to detect, identify, and classify power quality (PQ) disturbances. For research on PQ analysis, it is critical to apply the appropriate signal processing techniques and classifier to solve PQ problems. The aim of this paper is to develop a classification method based on the combination of Hilbert transform (HT) and support vector machine (SVM) for the assessment of power quality events. Recent data mining literature has shown that support vector machine methods generally outperform traditional statistical and neural methods in classification problems involving power disturbance signals. The features obtained from the Hilbert transform are distinct, understandable and immune to noise. Analysis is presented to verify that the merits of HT and SVM combination make it adequate for PQ analysis when compared with the existing techniques in the literature.

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Howell, Robert. "The Russellian Monist's Problems with Mental Causation". Philosophical Quarterly 65, nr 258 (29.09.2014): 22–39. http://dx.doi.org/10.1093/pq/pqu058.

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Kaleybar, Hamed Jafari, Morris Brenna, Federica Foiadelli, Seyed Saeed Fazel i Dario Zaninelli. "Power Quality Phenomena in Electric Railway Power Supply Systems: An Exhaustive Framework and Classification". Energies 13, nr 24 (17.12.2020): 6662. http://dx.doi.org/10.3390/en13246662.

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Electric railway power systems (ERPS) as one of the most critical and high-power end-user loads of utility grids are characterized by outlandish power quality (PQ) problems all over the world. The extension and evolution of different supply topologies for these systems has resulted in significant and various forms of distortions in network voltage and current in all ERPS, the connected power system, and adjacent consumers. During the last years, numerous studies have been offered to investigate various aspects of PQs in a specific supplying topology. Variation in the supply structure of the ERPS and different types of locomotives has propelled the observation of different PQ phenomena. This versatility and development have led to confront considerable types of two-way interactive interfaces as well as reliability and PQ problems in ERPS. In addition, the lack of standards explicitly dedicated to ERPS has added to the ambiguity and complexity of this issue. In this paper, an extensive review of PQ distortions and phenomena in different configurations of ERPS is proposed and a systematic classification is presented. More than 140 scientific papers and publications are studied and categorized which can provide a fast review and a perfect perspective on the status of PQ indexes for researchers and experts.

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Bharatiraja, C., i Harish Chowdary V. "Real Time Power Quality Phenomenon for Various Distribution Feeders". Indonesian Journal of Electrical Engineering and Computer Science 3, nr 1 (1.07.2016): 10. http://dx.doi.org/10.11591/ijeecs.v3.i1.pp10-16.

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Power Quality (PQ) brings more challenges to the large- scale and medium scale industries because in the recent years most of them use high efficiency and low energy devices which cause vulnerable PQ disturbances at Point of Common Coupling (PCC). In this paper, the measurement at different times during load condition and analysis of all types of disturbances occurred has been done. When large rated equipments run, the disturbance (harmonics, RMS variations, and switching transients) levels are very high and poor power factor (PF) has also appeared. Due to this poor PF, reactive power consumption in load increases and accordingly total power increases. An electronic device such as LED lights, fluorescent lamps, computers, copy machines, and laser printers also disturb the supply voltage. We are very well known that every PQ problem directly or indirectly must affect economically. Many researchers have investigated PQ audit for over three decades. However these studies and analysis have been done only at simulation level. Hence, the PQ analyzer based study is required to find out the PQ issues at distribution feeders. It will be a valuable guide for researchers, who are interested in the domain of PQ and wish to explore the opportunities offered by these techniques for further improvement in the field of PQ. This paper gives a brief Real Time PQ measurement using PQ analyzer HIOKI PW3198 at Distribution Feeders and it gives an idea to the researcher to optimize problems-related to PQ with respect to the high rated and low rated electric machinery of different feeders at PCC level. This study further extends to analyze the grid disturbances and looks forward to the optimization methods for each individual PQ disturbance.

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Alhaiz, Hussain A., Ahmed S. Alsafran i Ali H. Almarhoon. "Single-Phase Microgrid Power Quality Enhancement Strategies: A Comprehensive Review". Energies 16, nr 14 (24.07.2023): 5576. http://dx.doi.org/10.3390/en16145576.

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Renewable distributed generators (RDGs) have made inroads in recent power systems owing to the environmental effect of traditional generators and their high consumption of electric energy. The widespread use of RDGs has been a recent trend in numerous nations. The integration complexity and the intermittent nature of RDGs can undermine the security and stability of microgrids (µGs). In order to guarantee the effectiveness, dependability, and quality of the electricity delivered, appropriate control methods are necessary. RDGs are being included in single-phase microgrids (1Ø-µGs) to generate energy closer to the user. The creation of low-voltage µGs allows for increased energy efficiency and improved electrical supply dependability. Nevertheless, the combined power pumped by DGs might create power quality (PQ) difficulties, especially during off-grid operations. The three biggest problems with PQ are reactive-power swapping, voltage and frequency (VαF) variations, and current and voltage (IαV) harmonic falsification associated with 1Ø-µGs; these conditions may affect the operation of µGs. The designed and implemented (primary–secondary control systems) in RDGs are the prevalent strategy discussed in the literature for mitigating these PQ difficulties. Furthermore, emerging grid innovations like the electrical spring offer viable alternatives that might reduce some problems through decentralized operation. Although several research studies have addressed PQ concerns in 3Ø-µGs, not all of these solutions are immediately applicable to their 1Ø equivalents. In this paper, the state of the art and a performance comparison of several PQ enhancement strategies of µGs is discussed. Additionally, the primary difficulties and several PQ approach tactics are highlighted. All vital features from high-quality published articles and new dimensions in this field are presented for mitigating PQ difficulties in 1Ø-µGs.

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Ibrahim, Nagwa F., Abdulaziz Alkuhayli, Abderrahmane Beroual, Usama Khaled i Mohamed Metwally Mahmoud. "Enhancing the Functionality of a Grid-Connected Photovoltaic System in a Distant Egyptian Region Using an Optimized Dynamic Voltage Restorer: Application of Artificial Rabbits Optimization". Sensors 23, nr 16 (13.08.2023): 7146. http://dx.doi.org/10.3390/s23167146.

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Photovoltaic (PV) systems are crucial to the production of electricity for a newly established community in Egypt, especially in grid-tied systems. Power quality (PQ) issues appear as a result of PV connection with the power grid (PG). PQ problems cause the PG to experience faults and harmonics, which affect consumers. A series compensator dynamic voltage restorer (DVR) is the most affordable option for resolving the abovementioned PQ problems. To address PQ difficulties, this paper describes a grid-tied PV combined with a DVR that uses a rotating dq reference frame (dqRF) controller. The main goal of this study is to apply and construct an effective PI controller for a DVR to mitigate PQ problems. The artificial rabbits optimization (ARO) is used to obtain the best tune of the PI controller. The obtained results are compared with five optimization techniques (L-SHADE, CMAES, WOA, PSO, and GWO) to show its impact and effectiveness. Additionally, Lyapunov’s function is used to analyze and evaluate the proposed controller stability. Also, a mathematical analysis of the investigated PV, boost converter, and rotating dqRF control is performed. Two fault test scenarios are examined to confirm the efficacy of the suggested control approach. The parameters’ (voltage, current, and power) waveforms for the suggested system are improved, and the system is kept running continuously under fault periods, which improves the performance of the system. Moreover, the findings demonstrate that the presented design successfully keeps the voltage at the required level with low THD% values at the load side according to the IEEE standards and displays a clear enhancement in voltage waveforms. The MATLAB/SIMULINK software is used to confirm the proposed system’s performance.

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Esmail, Yahia M., Ali H. Kasem Alaboudy, M. S. Hassan i Gamal M. Dousoky. "Mitigating power quality disturbances in smart grid using FACTS". Indonesian Journal of Electrical Engineering and Computer Science 22, nr 3 (1.06.2021): 1223. http://dx.doi.org/10.11591/ijeecs.v22.i3.pp1223-1235.

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Power quality (PQ) assurance is a vital part of electrical distribution networks. There are many advantages and benefits of improving PQ, especially in the modern/smart grid. Smart grid (SG) has a lot of complicated and sensitive electrical components (non-linear loads) in addition to renewable energy systems (wind-solar) that may also be a source of PQ disturbances. PQ problems harm personal life and national production. Static synchronous compensator (STATCOM) and unified power quality conditioner (UPQC) are among the fastest response flexible alternating current transmission systems (FACTS) installed in smart grids to mitigate power quality disturbances such as voltage fluctuations, sag, swell, and harmonics. In this research, STATCOM and UPQC are designed and simulated in MATLAB/Simulink to overcome PQ-related disruptions in smart grids. Accordingly, the differences between the proposed two solutions are highlighted across this research and renewable energy sources' reliability during faults. Therefore, the reader will be able to choose the appropriate FACTS devices. This study emphasizes the extent of the smart grid need for the FACTS. As per the given results of this study, STATCOM and UPQC have shown exemplary performance in the PQ improvement investigations conducted in the context of smart/modern grids.

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Cahill, Kevin. "The Nature of Philosophical Problems: Their Causes and Implications". Philosophical Quarterly 66, nr 263 (25.06.2015): 406–8. http://dx.doi.org/10.1093/pq/pqv054.

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Guivant, Jose, Brett Seton i Mark Whitty. "2D Path Planning Based on Dijkstra's Algorithm and Pseudo Priority Queues". Proceedings of the International Symposium on Combinatorial Search 3, nr 1 (20.08.2021): 206. http://dx.doi.org/10.1609/socs.v3i1.18255.

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This paper presents the application of the PPQ Dijkstra approach for solving 2D path planning problems. The approach is a Dijkstra process whose priority queue (PQ) is implemented through a Pseudo Priority Queue (PPQ) also known as Untidy PQ. The performance of the optimization process is dramatically improved by the application of the PPQ. This modification can be used for a family of problems. The path planning problem belongs to the family of feasible problems that can be solved by considering PPQ-Dijkstra approach. The solution provided by the PPQ-Dijkstra algorithm is optimal, i.e. it is identical to the solution obtained through the standard Dijkstra algorithm. The PPQ-Dijkstra algorithm can be also applied for higher dimensionality problems such as non-holonomic planning processes, e.g. involving configuration spaces of higher dimension.

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Wei, Tian Cai, Shun Tao, Bin Su i Chao Luo. "Current Detection Method and its Application of an Extension pq Theory". Applied Mechanics and Materials 668-669 (październik 2014): 907–10. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.907.

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In the modern society, with the rapid development of industrial technology and information industry, electrical loads become more and more complex. As a result, the harmonics and reactive power problems have become increasingly serious. In the non-sinusoidal conditions, conventional power definitions don’t work well any more. Power theory is one of the foundations of financial accounts for energy, evaluation of the efficiency of power transmission and control of current compensation. Among them, the instantaneous reactive power theory is regarded as one of the most promising power theories. What’s more, it has been improved. Based on the three-phase three-wire system and four kinds of different supply voltage conditions, this paper compares the instantaneous reactive power theory (pq theory) with the extension pq theory. At last, the simulation results are presented. As a conclusion, the extension pq theory is the improvement of the pq theory and has a wider applicability.

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DU, GAO-XIANG, HAO HE, LI-BING LIAO i LI-JUAN WANG. "MECHANO-CHEMICAL PREPARATION OF POWDER QUARTZ/TiO2 COMPOSITE PARTICLES". Surface Review and Letters 20, nr 02 (kwiecień 2013): 1350016. http://dx.doi.org/10.1142/s0218625x13500169.

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Titanium dioxide pigment is a white pigment of high performance. However, its production could cause severe environmental and resource problems. In this paper, powder quartz/ TiO2 composite particles (PQ/TCP), a type of core (powder quartz)–shell( TiO2 ) composite powder, were prepared by a mechano-chemical method. The pigment properties of PQ/TCP and the mechanism of the mechano-chemical reaction between quartz and TiO2 were investigated. Orthogonal analyses of experimental vairables showed optimal pigment characteristics of PQ/TCP under the following conditions: 4 h of activation for powder quartz, mixing/grinding at 1000 rpm for 1 h, with a mixing slurry made of 50% powder quartz and 0.4% dispersant. Powder quartz was evenly coated by TiO2 and the Si–O–Ti bond was formed between powder quartz and TiO2 in PQ/TCP as revealed by FTIR analyses and confirmed by surface thermodynamic calculation.

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Gamasu, Ramesh. "Load flow Pseudo-inverse and Magnitude Conversions for Mitigation of PQ Problems using DVR". International Journal of Advanced Science and Technology 60 (30.11.2013): 9–24. http://dx.doi.org/10.14257/ijast.2013.60.02.

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Reddy, Ch Rami, B. Srikanth Goud, Flah Aymen, Gundala Srinivasa Rao i Edson C. Bortoni. "Power Quality Improvement in HRES Grid Connected System with FOPID Based Atom Search Optimization Technique". Energies 14, nr 18 (14.09.2021): 5812. http://dx.doi.org/10.3390/en14185812.

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An intelligent control strategy is proposed in this paper which suggests the Optimum Power Quality Enhancement (OPQE) of grid-connected hybrid power systems with solar photovoltaic, wind turbines, and battery storage. Unified Power Quality Conditioner with Active and Reactive power (UPQC-PQ) is designed with Atom Search Optimization (ASO) based Fractional-order Proportional Integral Derivative (FOPID) controller in the proposed Hybrid Renewable Energy Sources (HRES) system. The main aim is to regulate voltage while reducing power loss and reducing Total Harmonic Distortion (THD). UPQC-PQ is used to mitigate the Power Quality (PQ) problems such as sag, swell, interruptions, real power, reactive power and THD reductions related to voltage/current by using ASO based FOPID controller. The developed technique is demonstrated in various modes: simultaneous to improve PQ reinforcement and RES power injection, PRES > 0, PRES = 0. The results are then compared to those obtained using previous literature methods such as PI controller, GSA, BBO, GWO, ESA, RFA, and GA and found the proposed approach is efficient. The MATLAB/Simulink work framework is used to create the model.

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Gade, Swati, Rahul Agrawal i Ravindra Munje. "Recent Trends in Power Quality Improvement: Review of the Unified Power Quality Conditioner". ECTI Transactions on Electrical Engineering, Electronics, and Communications 19, nr 3 (31.10.2021): 268–88. http://dx.doi.org/10.37936/ecti-eec.2021193.244936.

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The electrical power sector is currently focusing on power quality (PQ) issues and their mitigation. Industrial automation and the use of power electronic converters for the integration of distributed generation create various PQ problems. This necessitates PQ enhancement, which in turn helps to improve the life span of the equipment as well as the reliability of supply for feeding critical loads within the system. This paper presents a comprehensive review of the Unified Power Quality Conditioner (UPQC) and its widespread application in the distribution system. The UPQC belongs to the family of active power filters. It contributes to the alleviation of voltage and current-related PQ issues along with power factor correction and the integration of renewable energy systems in the distribution network. This paper discusses various topologies, compensation methods, control theories, and the technological developments in recent years. More than 160 research papers have summarized the features of UPQC for further applications. Based on the outcomes of the investigation, the future direction of the UPQC is discussed. This paper is expected to play a major role in guiding research scholars in the application of the UPQC.

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DEKHANDJI, Fatma Zohra, Salim TALHAOUI i Youcef ARKAB. "Power Quality Detection, Classification and Monitoring Using LABVIEW". Algerian Journal of Signals and Systems 4, nr 2 (15.12.2019): 101–11. http://dx.doi.org/10.51485/ajss.v4i2.86.

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In recent years, Power Quality becomes increasingly a major concern for both electric utilities and end users. Accordingly, the electrical engineering community has to deal with the analysis, diagnosis and solution of PQ issues using system approach rather than handling these issues as individual problems. This paper describes the analysis of PQ using advanced signal processing tools represented in Hilbert & Wavelet Transforms (HT-WT) and artificial intelligence tools represented in Artificial Neural Network & Support Vector Machine (ANN-SVM) for detection and classification of power quality disturbances respectively. These techniques were successfully simulated using LABVIEW software capabilities. The results of simulation indicate that the signal processing techniques are effective mechanisms to detect and classify power quality disturbances. At the end, the combination of WT as a tool of detection and features extraction with SVM as a classifier tool resulted as the best combination for PQ monitoring system.

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Arov, D. Z., B. Fritzsche i B. Kirstein. "On Some Completion Problems for Various Subclasses of $j_{pq}$-inner Functions". Zeitschrift für Analysis und ihre Anwendungen 11, nr 4 (1992): 489–508. http://dx.doi.org/10.4171/zaa/589.

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Singh, Pradeep, Krishan Arora i Umesh C. Rathore. "Control Strategies for Improvement of Power Quality in Grid Connected Variable Speed WECS with DFIG – An Overview". Journal of Physics: Conference Series 2327, nr 1 (1.08.2022): 012008. http://dx.doi.org/10.1088/1742-6596/2327/1/012008.

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Abstract The presented paper gives a detailed observation of the PQ related problems for WE based on the EFIG or DFIG (Extra or Doubly Fed Induction Generator. Fundamental Frequency Components are the most typical reasons of disruption of power quality. On the other hand, wind loading conditions also disrupt the power quality. Numerous modes for the removing of these problems were studied to get the rid of these fundamental frequency components of the WES (Wind Energy Systems). In the presented paper, there is substantial analysis of numerous controlling techniques were presented to eliminate these PQ and different loading conditions i.e. grid conditions and wind loading conditions. Furthermore, utilizing the WECS (Wind Energy Conversion System) as an operative filter. This analysis of DFIG based WECS help research scholars to choose the adequate control procedures while utilizing the WECS as an operative filter.

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Prasad, Devalraju, i C. Dhanamjayulu. "A Review of Control Techniques and Energy Storage for Inverter-Based Dynamic Voltage Restorer in Grid-Integrated Renewable Sources". Mathematical Problems in Engineering 2022 (29.09.2022): 1–43. http://dx.doi.org/10.1155/2022/6389132.

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Power quality (PQ) is a key issue, particularly for technologically advanced process equipment, whose performance mainly depends on the quality of supply. Problems with PQ such as voltage swells/sags, interruptions, and harmonics are defined by any voltage, current, or frequency abnormalities causing damage or failure of the end-user equipment. Outages and interruptions lead to malfunctioning of end-user equipment or sensitive loads, such as diagnostic equipment in healthcare facilities, clinics, educational institutions, and detention centers, while further increasing significant economic losses. Custom power devices (CPDs) are recommended for enhancing power quality, and the best and most economical solution is considered to be the dynamic voltage restorer (DVR). Several methods are suggested to improve the PQ by using the dynamic voltage restorer; among them, most encouraging ways are to use a multilevel inverter (MLI) in the dynamic voltage restorer. This article combines the latest work of the literature, as well as a detailed discussion on PQ issues of the grid-integrated renewable energy sources (RESs), DVR principle with its operating procedures, system components, energy storage-based DVR topologies, DVR control unit, and DVR power converter-based topologies. In addition, synthesis of energy storage, control strategies, and multilevel inverters for DVR. This review benefits those interested in investigating DVR as a relevant and comprehensive reference.

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Tzinman, Rina. "Thinking Parts and Embodiment". Philosophical Quarterly 71, nr 1 (1.06.2020): 163–82. http://dx.doi.org/10.1093/pq/pqaa020.

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Abstract According to the thinking parts problem, any part sufficient for thought—e.g. a head—is a good candidate for being a thinker, and therefore being us. So we can’t assume that we—thinkers—are (or are constituted by) human beings rather than their proper parts. Many solutions to this problem have been proposed. However, I will show that the views currently on the market all face serious problems. I will then offer a new solution that avoids these problems. The thinking parts problem arises from considerations that seem to be empirically substantiated. One virtue of my solution is that in addition to its theoretical apparatus it appeals to empirically substantiated considerations.

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Lewens, Tim. "Species Natures: A Critique of Neo-Aristotelian Ethics". Philosophical Quarterly 70, nr 280 (29.11.2019): 480–501. http://dx.doi.org/10.1093/pq/pqz080.

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Abstract This paper examines the neo-Aristotelian account of species natures as ‘life-forms’, which we owe to Philippa Foot, Michael Thompson and their defenders. I begin by developing two problems for their view: a problem of underdetermination and a problem generated by psychological work on ‘folk essentialism’. I move on to consider their important transcendental argument, which suggests that claims about life-forms are presupposed by all efforts to describe the organic world. In response, I sketch a neo-Kantian projectivist position, which agrees that life-forms are presupposed in these contexts, while denying that such life-forms are real. This position makes a better sense of the phenomena cited in support of the neo-Aristotelian view, while avoiding the problems raised for that view in the first half of this paper.

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Ehtesham, Mohammad, i Md Junaid. "Advanced compensation scheme for enhancing photovoltaic power quality". Indonesian Journal of Electrical Engineering and Computer Science 27, nr 3 (1.09.2022): 1223. http://dx.doi.org/10.11591/ijeecs.v27.i3.pp1223-1230.

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With the photovoltaic (PV) system becoming highly popular in distribution network, there is also a growing concern regarding its adverse impacts over the power quality (PQ) of integrated system. This deterioration in PQ hassparked a new interest in the filtering techniques used in the power systemfor mitigating these problems. In contrast to conventional passive filters now active power filters (APFs) are being looked as the predominant solution.This paper presents a state-estimation based effective compensation strategy for enhancing performance of employed APF scheme. A novel control technique for PQ enhancement is proposed where Kalman filtering approach has been applied for generating the reference signals. Also, an adaptive hysteresis band technique has been applied here in the switching strategy. Thus an enhanced filter performance is achieved with reduced complexity and better elimination of distortions. Simulated results obtained in MATLAB/Simulink platform have been analyzed completely, where the superiority of filtering algorithm has been also demonstrated through leasttotal harmonic distortion (THD) achieved in source current among all the existing Kalman filters.

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Mubdir, Bilal A., i Dara H. Amin. "Phase Sequence Online Correction Based on PIC Technique". International Journal of Advances in Applied Sciences 6, nr 1 (1.03.2017): 49. http://dx.doi.org/10.11591/ijaas.v6.i1.pp49-54.

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Monitoring the delivered power quality (PQ) to a critical load, is a worry issue since it is matter as much as critical or quality sensitive equipment connected to the electrical network. Various PQ problems such as noise, voltage imbalance, waveform distortion, phase imbalance, phase sequence, over voltage or sag are the most popular quality problems that could be detected and fixed if needed. The present work presents a design and practical implementation of electronic embedded system to monitoring the sequence of a three phase electrical system and detects the occurrence of any change in the sequence and fixes it online, correct the phase sequence immediately during less than 70 milli-seconds. PIC Microchip microcontroller has been used as the core of the present system, where the correction of the phases has been achieved by using traditional electromechanical relays. The system has been tested successfully and it functions properly even with multiple sequence changes.

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Moya, J., F. Balada, A. Blanch i A. Aluja. "The ZKA-PQ and its association with alcohol use problems: A mediational analysis". Personality and Individual Differences 60 (kwiecień 2014): S76. http://dx.doi.org/10.1016/j.paid.2013.07.340.

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Carter, J. Adam. "De Minimis Normativism: a New Theory of Full Aptness". Philosophical Quarterly 71, nr 1 (20.04.2020): 16–36. http://dx.doi.org/10.1093/pq/pqaa017.

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Abstract Full aptness is the most important concept in performance-based virtue epistemology. The structure of full aptness, in epistemology and elsewhere, is bilevelled. At the first level, we evaluate beliefs, like performances, on the basis of whether they are successful, competent, and apt—viz successful because competent. But the fact that aptness itself can be fragile—as it is when an apt performance could easily have been inapt—points to a higher zone of quality beyond mere aptness. To break in to this zone, one must not merely perform aptly but also in doing so safeguard in skilled ways against certain risks to inaptness. But how must this be done, exactly? This paper has two central aims. First, I challenge the credentials of mainstream thinking about full aptness by raising some new and serious problems for the view. I then propose a novel account of full aptness—what I call de minimis normativism—which keeps all the advantages of the canonical view, avoids its problems entirely, and offers some additional payoffs.

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Nouman, Danish, Intisar Ali Sajjad i Ahsan Ali. "Distribution Network Voltage Improvement using Dynamic Voltage Restorer with Smooth Super Twisting Sliding Mode Control". International Conference on Scientific and Innovative Studies 1, nr 1 (14.04.2023): 446–53. http://dx.doi.org/10.59287/icsis.638.

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Sensitive industrial customers need higher Power Quality (PQ). End-users and electrical utilityfirms are both paying more attention to PQ problems as a result of massive financial losses caused by PQproblems to sensitive industrial loads. The most important and frequently recurring PQ problems in asecondary distribution system are voltage sags and swells. A rapid, adaptable, dynamic Custom PowerDevice called the Dynamic Voltage Restorer can be utilized to reduce voltage sags and swells. The controlapproach selected for switching Voltage Source Converters (VSCs) largely determines its performance. Byusing the Sliding Mode Control (SMC) with Smooth Super Twisting Algorithm (SSTA), this researchsuccessfully removes the effects of voltage sags and swells on the VSC of DVR. When SSTA is used inconjunction with conventional SMC, chattering, a downside of SMC, is reduced while keeping otheradvantages including robustness, shorter response times, and insensitivity to changings in the load. Theefficiency of this technique is evaluated using the MATLAB/Simulink SimPower System toolbox. Thesimulation's findings demonstrate that the Smooth Super Twisting Sliding Mode Controller (SSTSMC) forDVR device can identify and compensate the voltage sags/swells in less than 2 milliseconds (ms), which issignificantly less time than the 20 milliseconds allowed limit of SEMI F-47 standard for sensitive loads andthe values of Total Harmonics Distortion (THD) is less than 5%. The comparative study also performedbetween Real Twisting Algorithm (RTA) and proposed technique Smooth Super Twisting Algorithm(SSTA), which shows that performance of proposed SSTSMC is much better than RTA.

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Chheepa, Tarun Kumar, i Tanuj Manglani. "Power Quality Events Classification using ANN with Hilbert Transform". International Journal of Emerging Research in Management and Technology 6, nr 6 (29.06.2018): 227. http://dx.doi.org/10.23956/ijermt.v6i6.274.

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With the evolution of Smart Grid, Power Quality issues have become prominent. The urban development involves usage of computers, microprocessor controlled electronic loads and power electronic devices. These devices are the source of power quality disturbances. PQ problems are characterized by the variations in the magnitude and frequency in the system voltages and currents from their nominal values. To decide a control action, a proper classification mechanism is required to classify different PQ events. In this paper we propose a hybrid approach to perform this task. Different Neural topologies namely Cascade Forward Backprop Neural Network (CFBNN), Elman Backprop Neural Network (EBPNN), Feed Forward Backprop Neural Network (FFBPNN), Feed Forward Distributed Time Delay Neural Network (FFDTDNN) , Layer Recurrent Neural Network (LRNN), Nonlinear Autoregressive Exogenous Neural Network (NARX), Radial Basis Function Neural Network (RBFNN) along with the application of Hilbert Transform are employed to classify the PQ events. A meaningful comparison of these neural topologies is presented and it is found that Radial Basis Function Neural Network (RBFNN) is the most efficient topology to perform the classification task. Different levels of Additive White Gaussian Noise (AWGN) are added in the input features to present the comparison of classifiers.

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Macii, Francesca, Rebecca Detti, Francesca Rita Bloise, Stefania Giannarelli i Tarita Biver. "Spectroscopic Analysis of the Binding of Paraquat and Diquat Herbicides to Biosubstrates". International Journal of Environmental Research and Public Health 18, nr 5 (2.03.2021): 2412. http://dx.doi.org/10.3390/ijerph18052412.

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The study of the interaction of persistent organic pollutants with biosubstrates helps to unravel the pathways for toxicity, however, few mechanistic data are present in the literature for these systems. We analyzed the binding of paraquat (PQ) and diquat (DQ) herbicides to natural calf thymus DNA and a DNA G-quadruplex by spectrophotometric titrations, ethidium bromide exchange tests, viscometry, and melting experiments. The interaction with bovine serum albumin (BSA) protein was studied spectrofluorimetrically at different temperatures. The retention of the targets on positive, negative, and neutral micellar aggregates and liposomes was analyzed by ultrafiltration experiments. Despite some favorable features, PQ and DQ only externally bind natural DNA and do not interact with DNA oligonucleotides. Both herbicides bind bovine serum albumin (BSA). PQ binds BSA mainly according to an electrostatics-driven process. However, ultrafiltration data also show that some hydrophobic contribution participates in the features of these systems. The practical problems related to unfavorable spectroscopic signals and inner filter effects are also discussed. Overall, both herbicides show a low affinity for nucleic acids and weak penetration into liposomes; in addition, the equilibrium constants values found for BSA system suggest optimal conditions for transport in the body.

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Manoj, Vasupalli, Prabodh Khampariya i Ramana Pilla. "A review on techniques for improving power quality: research gaps and emerging trends". Bulletin of Electrical Engineering and Informatics 11, nr 6 (1.12.2022): 3099–107. http://dx.doi.org/10.11591/eei.v11i6.4396.

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Many issues have arisen for the electricity sector because of the widespread use of gadgets that rely on electrical power. India's energy demands are rising rapidly due to the country's rapid economic development. These days, almost every industry makes extensive use of electrical machinery and equipment. Electronic gadgets add a non-linear demand to the power grid, which can cause power quality (PQ) problems such as voltage fluctuations that can damage electrical equipment and even knock the grid down. As the use of DG units becomes more commonplace, complications related to power conversion interfaces, load switching, and other factors emerge as potential bottlenecks in service. Power filters were first created several decades ago to address problems with PQ and to dampen harmonics caused by nonlinear loads. This document summarises previous studies that have investigated the effectiveness of power filters and other techniques for enhancing power quality. There are also descriptions of research that is still going on and where it stands, as well as a look ahead to what its possible future benefits might be.

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Jaswini Sarwade, Te, V. S. Jape i D. G. Bharadwaj. "Power quality problems mitigation using dynamic voltage restorer (DVR) with pi controller and fuzzy logic controller". International Journal of Engineering & Technology 7, nr 2.12 (3.04.2018): 214. http://dx.doi.org/10.14419/ijet.v7i2.12.11282.

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The existence of non-standard currents, frequencies and voltages enhances the Power Quality (PQ) problems. Power consumed by the consumers and losses occurred in power system are deciding factors for the utility to determine the performance of the power system in terms of Power Quality. These Power Quality problems lead to failure of end user equipments as well as creates disturbances in power distribution network, thereby deteriorates residual life assessment of major equipments used in substation. The PQ problems can be characterized as voltage surges, sags, swells, harmonic distortions, etc. There are many reasons for the determination of Power Quality. The loads used by the consumers of electricity abnormally leads to deprove the Power Quality. Low power factor loads are taken care of by the utilities in the form of financial penalty. However, occurrence of harmonics, voltage swells and sags in the system is the most powerful reason behind degradation of Power Quality. To mitigate these issues, use of Custom Power Devices (CPD) in the distribution network is the most significant solution. Paper presents the design of the CPD like Dynamic Voltage Restorer (DVR) using two control strategies i.e. PI Controller and Fuzzy Logic Controller (FLC). MATLAB/SIMULINK is used to analyze the effectiveness of these control strategies.

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Das, Soumya Ranjan, Prakash K. Ray, Arun Kumar Sahoo, Somula Ramasubbareddy, Thanikanti Sudhakar Babu, Nallapaneni Manoj Kumar, Hassan Haes Alhelou i Pierluigi Siano. "Performance of Hybrid Filter in a Microgrid Integrated Power System Network Using Wavelet Techniques". Applied Sciences 10, nr 19 (28.09.2020): 6792. http://dx.doi.org/10.3390/app10196792.

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Nowadays, the application of distributed energy sources (DES) has been extensively employed to serve the power system by supplying the power into the grid and improving the power quality (PQ). Therefore, DES is one solution that can efficiently overcome the energy crisis and climate change problems. The DES, such as solar photovoltaic (PV), wind turbine (WT), and battery energy storage systems (BESS), are incorporated to form the microgrid (MG), which are interfaced with the power system. However, interfacing MG to the power system is undoubtedly a big challenge. Therefore, more focus is required on the control strategy to control the MG with the power system. To address the PQ problems, a controlled MG integrated with a hybrid shunt active power filter (HSAPF) is provided in this work. For controlling the MG integrated HSAPF, different control strategies are applied. In this work, a learning-based incremental conductance (LINC) technique is used as a maximum power point tracking (MPPT) for tracking the maximum power in PV and WT. The voltage source inverter (VSI) of HSAPF is controlled using a wavelet-based technique with a synchronous reference frame (SRF). The main focus is to improve the PQ by compensating the harmonics and regulating the reactive power in both grid-interactive and islanded condition and also supply continuous and adequate power to the non-linear load. The power system model has been developed with MATLAB/Simulink tool, which shows the efficiency of the proposed method. The results obtained have been satisfactorily under various operating conditions and can be validated further using the real-time dSPACE.

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Jain, Preeti, Atul Kumar Tiwari i Sachin Kumar Jain. "Harmonic source identification in distribution system using estimation of signal parameters via rotational invariance technique-total harmonic power method". Transactions of the Institute of Measurement and Control 40, nr 12 (11.09.2017): 3415–23. http://dx.doi.org/10.1177/0142331217721316.

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With proliferation of power electronics devices in the distribution system, harmonic distortion has become one of the major power quality (PQ) problems. In evolving the liberalized electricity market, it becomes necessary to develop suitable methods to allocate the responsibilities for the harmonic distortion to improve the PQ. This paper presents a new technique for harmonic source identification, which is based on total harmonic power (THP) method using estimation of signal parameters via rotational invariance technique (ESPRIT). Traditionally, harmonic powers for THP method is computed using Fourier transform, which inherits serious drawbacks of the discrete and fast Fourier transform, namely, inaccuracy owing to poor spectral resolution, spectral leakage, and so forth. Simulation results have been presented for different distribution system configurations and conditions, which confirms the improved capabilities of the proposed method in harmonic source identification.

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GLASS, DARREN B. "A FROBENIUS QUESTION RELATED TO ACTIONS ON CURVES IN CHARACTERISTIC P". Glasgow Mathematical Journal 56, nr 1 (13.08.2013): 143–48. http://dx.doi.org/10.1017/s0017089513000128.

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AbstractWe consider which integers g can occur as the genus and of a curve defined over a field of characteristic p which admits an automorphism of degree pq, where p and q are distinct primes. This investigation leads us to consider a certain family of three-dimensional Frobenius problems and prove explicit formulas giving their solution in many cases.

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Dubais, Ahmed M. A., i Abdulaziz M. S. Al-Dobhani. "Study of Power Quality Problems in Yemeni Educational Buildings". Journal of Science and Technology 20, nr 2 (11.12.2015): 45–47. http://dx.doi.org/10.20428/jst.v20i2.939.

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Power Quality (PQ) has become a big issue since the late 1980s. Equipments which are in use nowadays, require good power quality. However, the pure sinusoidal voltage or current waveform is distorted by the nonlinear properties of the equipments. The main purpose of this paper is to investigate the most common problems in power quality in educational buildings and propose a solution for the main dominate one. The Point of Common Coupling (PCC) was elected to be an incomer breaker. The study includes monitoring and measuring the power waveform for one week. The result are analyzed and compared with International Standards. Interruptions are the main problem while swells, dips and transients problems are caused as a result of the interruptions problems.

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Blanton, Matthew. "The art of the possible: A call for political intelligence (PQ) in missiological reflection". Missiology: An International Review 46, nr 4 (16.08.2018): 350–62. http://dx.doi.org/10.1177/0091829618785615.

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Missiology has always drawn heavily from other academic disciplines, particularly sociology and cultural anthropology. With the desire to engage intelligently across cultures, missiologists employ specific anthropological tools and methods and stress that missionaries need “CQ” or “cultural intelligence” in order to be effective. Similarly, missiologists have increasingly argued that the gospel necessarily includes a political dimension. However, unlike the sophisticated engagement with “culture,” the calls for political involvement rarely go much deeper. Researchers often point to political structures and problems and call for the church to respond, without offering any ideas on how to effect change practically. Furthermore, there is a glaring lack of engagement with political science and other disciplines that specialize in how policies are changed in the real world. I argue that “PQ” or political intelligence is desperately needed in order to inform and support missiological reflection and strategy on political issues. It is not enough to simply want to influence political systems for Kingdom purposes, we must seek PQ. This is acquired through missiological interaction with political science and the adoption of best practices from the non-academic activist community. I end by presenting several political science concepts that will guide missiology moving forward in its embrace of PQ.

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Li, T. Y. "Numerical solution of multivariate polynomial systems by homotopy continuation methods". Acta Numerica 6 (styczeń 1997): 399–436. http://dx.doi.org/10.1017/s0962492900002749.

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Let P(x) = 0 be a system of n polynomial equations in n unknowns. Denoting P = (p1,…, pn), we want to find all isolated solutions offor x = (x1,…,xn). This problem is very common in many fields of science and engineering, such as formula construction, geometric intersection problems, inverse kinematics, power flow problems with PQ-specified bases, computation of equilibrium states, etc. Elimination theory-based methods, most notably the Buchberger algorithm (Buchberger 1985) for constructing Gröbner bases, are the classical approach to solving (1.1), but their reliance on symbolic manipulation makes those methods seem somewhat unsuitable for all but small problems.

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Lee, Chih-Hung, i Men-Shen Tsai. "Application of a Hybrid Method for Power System Frequency Estimation with a 0.2-second Sampled Period". MATEC Web of Conferences 201 (2018): 02007. http://dx.doi.org/10.1051/matecconf/201820102007.

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The signal processing technique is one of the principal tools for diagnosing power quality (PQ) issues in electrical power systems. The Discrete Fourier Transform (DFT) is a frequency analysis technique used to process power system signals and identify PQ problems. However, the DFT algorithm may lead to spectral leakage and picket-fence effect problems for asynchronously sampled signals that contain harmonic, inter-harmonic, and flicker components. To resolve this shortcoming, a hybrid method for frequency estimation based on a second-level DFT approach and a frequency-domain interpolation algorithm to obtain the accurate fundamental frequency of a power system is proposed in this paper. This method uses a second-level DFT to compute the cosine and sine parts for the fundamental frequency components of the acquired signals. Then, a frequency-domain interpolation approach is adopted to determine the amplitude ratio for the cosine and sine parts of the system’s fundamental frequency. A set of mixed signals with harmonic, inter-harmonic, and flicker components with the fundamental frequency deviation is used. The evaluation results demonstrate the superiority of the new method over other approaches for assessing asynchronously sampled signals contaminated with noise, harmonic, inter-harmonic, and flicker components.

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Bangarraju, J., V. Rajagopal, V. Sharada i K. Lakshmaiah. "Peak Detection Control Strategy based STATCOM for Suppression of Power Quality Problems". E3S Web of Conferences 87 (2019): 01027. http://dx.doi.org/10.1051/e3sconf/20198701027.

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This paper explains about control of VSC using uni-polar switching based Static Compensator (STATCOM) using Peak Detection Control Strategy for elimination of PQ Problems. The proposed STATCOM are operated in PFC (Power Factor Correction) mode and ZVR (Zero Voltage Regulation) mode. Under these operation modes of STATCOM is able to suppression of harmonics, PFC at source, reactive power compensation, load balancing and compensation of neutral current. A non-isolated star/three individual single- phase transformers are connected at PCC (Point of Common Coupling) to mitigate neutral current. The Peak Detection Control Strategy is simple to implement for estimating switching pulses for VSC. This peak detection control strategy based STATCOM is modelled, simulated results are validated using MATLAB R2013b.

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Haidar, S., E. Moussa, M. El Hassan i M. Badawi El Najjar. "Design of Power Quality Virtual Lab Toolbox using LabVIEW/Multisim". Renewable Energy and Power Quality Journal 19 (wrzesień 2021): 143–48. http://dx.doi.org/10.24084/repqj19.240.

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This paper presents a Power Quality (PQ) virtual lab that can be used by electrical engineers (EE) to enhance their knowledge and awareness on power quality disturbances in accordance to power quality standards. It will offer the EE the facility to become more aware about the problems tackling power systems and nonlinear devices, and their effects on the power quality indices. This work is built using NI LabVIEW/Multisim and is composed out of many simulations and experiments each with its learning objectives. The established measured power quality indices are mainly the root mean square (RMS), the total harmonic distortion (THD), the distortion index (DIN), the telephone influence factor (TIF), the crest factor (CF), the voltage transformer product (VT), the current transformer product (IT), the displacement power factor (DPF), the true power factor (TPF) and the unbalance factor (UF). Each of these indices is measured and analyzed in order to check how they are affected by the PQ issues.

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Vigneysh, T., i N. Kumarappan. "Grid Interconnection of Renewable Energy Sources Using Unified Power Quality Conditioner: A Fuzzy Logic-Based Approach". Journal of Circuits, Systems and Computers 28, nr 08 (lipiec 2019): 1950135. http://dx.doi.org/10.1142/s0218126619501354.

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This paper proposes distributed generation-integrated unified power quality conditioner (UPQC-DG) with adaptive fuzzy proportional–integral (AFPI) controller to improve the power quality (PQ) of a distribution network. In the proposed system, the DG units are integrated at dc-link of the UPQC to provide additional functionalities. The additional functionalities which are unique to the proposed system is to (i) export the available active power from renewable energy sources to the grid, (ii) compensate long term PQ problems, (iii) compensate voltage interruption. Additionally, the dc-link voltage of the system is controlled by using the proposed AFPI controller to effectively improve the dynamic performance of the system during disturbances. Unlike conventional PI controller, in the proposed controller, the gains are not fixed. It is dynamically adjusted by the fuzzy logic-based intelligent supervisory control system according to system operating conditions. The effectiveness of the proposed system is verified using extensive simulation studies and necessary results are compared with the existing literature.

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