Wyniki 1-10 spośród 40 dla zapytania: authorDesc:"AZAH MOHAMED"

A Reliable Maximum Power Point Tracker for Photovoltaic Systems

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This paper presents a reliable maximum power point tracker (MPPT) for photovoltaic (PV) systems. This MPPT tracks the maximum power point of a PV module by calculating the optimum resistance of the PV module at certain solar radiation level, ambient temperature value and load impedance. The calculated resistance is used to calculate the optimum duty cycle of the DC-DC converter triggering signal using a developed relation. Based on results, the proposed MPPT has better efficiency (95%) than perturbation and observation (P&O) method (92 %). Moreover, the proposed method is faster than P&O method because there is no perturbation around the MPP during the tracking process. Streszczenie. W artykule zaprezentowano układ śledzący maksymalną pobieraną moc dla system fotovoltaicznego. Moc jest wyznaczana na podstawie optymalnej rezystancji przy danym nasłonecznieniu, temperaturze otoczenia i impedancji obciążenia. Zaproponowany system jest bardziej skuteczny niż metoda zakłóceń I obserwacji P&O. (Skuteczny układ śledzenia maksymalnej mocy systemu fotowoltaicznego) Keywords: MPPT, PV systems, DC-DC buck converter. Słowa kluczowe: baterie słoneczne, śledzenie mocy. Introduction Recently, the maximum power point tracking technology becomes very important for photovoltaic systems. Consequently, many developments have been done in this area until it reached the saturation phase. As a result, the interest of the authors when implementing this work has been focused on achieving a certain added value in the proposed system, which can be found in the accurateness, speed and low cost [1]. Thus, the developed algorithm presents the advantage of its simplicity and its high speed which also helps to improve photovoltaic system efficiency. In general, to overcome the undesired effects on the output PV module’s power because of load variation , a DC/DC converter can be inserted between the PV generator and the load (batteries and typical loads), wh[...]

Study of Basic Properties of an Enhanced Controller for DVR Compensation Capabilities

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This paper deals with the development of an enhanced controller for investigation of dynamic voltage restorer (DVR) compensation capabilities. Two levels, 24-pulse DVR is modeled with a new control scheme to control the switch signal in the voltage sourced converter. A study on voltage sag compensation capability, harmonic elimination, effect of phase shift on DVR sizing, influence of induction motor load and effect of capacitor value on DVR performance have been investigated. Results proved that the DVR is a suitable device for maximum power quality (PQ) compensation. Thus, the developed model and controller will be useful for further power quality studies in a distribution system. Streszczenie. Opisano ulepszony sterownik system dynamicznego odzyskiwania napięcia DVR. Przeanalizowano przypadki możliwości kompensacji zapadów napięcia, eliminacji harmonicznych oraz wpływ indukcyjności obciążenia. Symulacje potwierdziły przydatność układu w systemach poprawy jakości energii. (Właściwości ulepszonego sterownika systemu DVR - dynamicznego odzyskiwania napięcia) Keywords: Control strategy, DVR, Voltage sag, Power quality. Słowa kluczowe: jakośc energii, zapady napięcia, odzyskiwanie napięcia. Introduction The increased concern for power quality has resulted a complete shutdown of an entire production line, in particular at high-tech industries like semiconductor plants, with severe economic consequence to the affected industries [1]-[2]. Many concepts have been developed in measuring power quality variations, studying the characteristics of power disturbances and providing solutions to the power quality problems [3]-[5]. Custom power is a concept based on the application of power electronic controllers in the distribution systems aimed at achieving a reliable and high quality power [6]-[11]. Dynamic voltage restorer (DVR) is custom power device, which has excellent dynamic capability for compensating short duration voltage sags [12]. It[...]

Utilization of fuel cell energy source for distribution power generation: theory, modeling and review of research work DOI:10.12915/pe.2014.05.044

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The energy crisis is one of the most critical phenomena happening in today’s world. The depletion of fossil fuels, the rise in oil prices, and the increase in power demand are the main causes of this problem. Concern over environmental conditions and human health make renewable energy one of the most viable alternative solutions to this crisis. Among various types of renewable energy, fuel cell technology shows a great potential in the electrical energy sector for several reasons, such as high efficiency, clean operation, and immunity to the adverse effects of weather conditions. Recent works prove that fuel cell technology is expected to be a better choice for distributed generation purposes. Distributed generation, which is installed near load centers, can moderate the stress of high electricity demand in the mainstream utility grid. This paper presents an overview of fuel cell technology, with emphasis on fuel cell types, characteristics, and applications. The differences among the various fuel cell types and the dynamic models of each type required for simulation are also discussed. Focus is given to the application of fuel cells in a distributed generation system, the requirements of a fuel cell-based generating system, and issues in distributed generation integration. The present study also discusses the power conditioning unit, which is an important component in the fuel cell-based generating system, as well as its control strategy. Discussion is likewise made on the use of suitable energy storage units for the fuel cell distributed generation system, with regard to battery types and storage control. By adding energy storage units to the fuel cell system, the capabilities of the existing generation system can improve system stability performance. Streszczenie. W artykule zaprezentowano przegląd technologii wytwarzania energii z wykorzystaniem ogniw paliwowych koncentrując się na analizie różnych typów i ich zastosowań. Szczególną[...]

Static Voltage Stability Analysis in a Distribution System with High Penetration of Photovoltaic Generation DOI:10.15199/48.2015.08.27

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This paper analyses the effect of grid-connected PV systems on static voltage stability using the IEEE 69 radial distribution system. The effect of integrating PV generators into power systems with higher PV penetration level and multiple numbers of PV generators is analyzed using PV curve and improved voltage stability index (IVSI). The P-V curve data show that grid-connected PV systems improve loading margin and voltage magnitude. The IVSI gives a positive output because systems with integrated PV generators reach the voltage collapse point. Streszczenie. W artykule analizowany jest wpływ podłączenia systemu fotowoltaicznego na na stabilność napięcia w radialnym systemie energetycznym IEEE 69. Analizowane są zależność P-V oraz indeks stabilności napięciowej IVSI. Podłączenie systemu fotowoltaicznego poprawia margines obciążenia sieci. Analiza statycznej stabilności napięciowej systemu energetycznego wzbogaconego o system fotowoltaiczny Keywords: Static voltage stability; Voltage collapse; solar PV generator; P-V curve; IVSI index. Słowa kluczowe: statyczna stabilność napięciowa, system fotowoltaiczny Introduction Modern infrastructures demand high-energy consumption with high quality and reliable electric power supply. Electric power utilities have difficulty answering these requirements due to the deficiency of conventional energy sources. Fossil fuels are a dense form of energy and thus requires millions years to develop. Therefore, renewable energy sources (RES) are introduced as a reliable form of energy to replace conventional energy sources. Wind power, solar energy, and hydropower are some examples of mainstream renewable technologies. Among those, solar energy has received much attention due to its promising energy, low installation cost, and lack of environmental pollution. Power system network design initially does not integrate any RES including solar PV. Small scale solar PV may not affect this network. However, integ[...]

Power quality diagnosis in distribution networks using support vector regression based S-transform technique

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This paper presents a novel method for performing automatic power quality diagnosis to identify the causes of short duration voltage disturbances such as voltage sags and swells. Such voltage disturbances can be caused by permanent or non permanent faults. A permanent fault causes permanent damage and power interruption to the customers whereas a non permanent fault can be categorized as either transient or incipient faults. In the proposed power quality diagnosis method, a time frequency analysis technique called as the S-transform is used to analyse and extract features of voltage disturbances recorded from the power quality monitoring system. The support vector regression which is an intelligent technique is then used identify whether the voltage disturbances are caused by permanent, non permanent, transient or incipient faults. Test results proved that the proposed power quality diagnosis method can provide accurate diagnosis on the causes of short duration voltage disturbances. Streszczenie. W artykule przedstawiono nową metodę przeprowadzania automatycznej diagnostyki jakości energii elektrycznej do identyfikacji przyczyn krótkoczasowych zakłóceń napięcia, takich jak zapady napięcia. Zaburzenia napięcia mogą być spowodowane przez długotrwałe lub chwilowe awarie. W proponowanej metodzie diagnozowania jakości zasilania, zastosowano transformatę S do ekstrakcji charakterystyk zarejestrowanych przebiegów z systemu monitoringu. Zastosowano regresję SVR jako technike inteligentna , pozwalajaca na rozróżnienie pomiędzy typami awarii.. Wyniki badań wykazały, że proponowana metoda diagnozowania jakości zasilania może zapewnić dokładną diagnozę na temat przyczyn zaburzeń napięcia o krótkim czasie trwania. (Analiza jakości energii w sieciach rozdzielczych w oparciu o transformatę S bazującą na regresji wektora wspierającego (SVR)) Keywords: power quality; power quality diagnosis; Support Vector Regression; S-transform Słowa kluczowe: jakość energ[...]

Application of artificial intelligent techniques in PSS design: a survey of the state-of-the-art methods

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Power system stabilizers (PSSs) are the most well known and efficient devices to damp the power system oscillations caused by interruptions. Low frequency oscillation problems are very difficult to solve because power systems are very large, complex and geographically distributed. Hence, it is necessary to employ most efficient optimization methods to take full advantages in simplifying the problem and its implementation. These optimization methodologies and techniques are widely diverse and have been the subject of ongoing enhancements over the years. This paper presents a survey of literature on the various optimization methods applied to solve the PSS problems. Streszczenie. System stabilizacji mocy PSS jest powszechnie stosowaną I skuteczną metodą tłumienia oscylacji spowodowanych przerwaniami. Oscylacje niskiej częstotliwości są trudne do eliminacji ze względu na ich złożoność i rozległość przestrzenną. Dlatego warto poszukiwać skutecznych metod optymalizacji metody PSS. Artykuł przedstawia metody optymalizacji wykorzystujące sztuczną inteligencję. (Wykorzystanie technik sztucznej inteligencji przy projektowaniu systemów stabilizacji mocy systemu energetycznego) Keywords: artificial intelligence techniques, optimization methods, power system stabilizer. Słowa kluczowe: sztuczna inteligencvja. Metody optymalizacji, stabilizacja w systemach energetycznych. 1. Introduction With the advent of automatic voltage regulators (AVRs) in the late 1950s, installation of AVRs on power generating units become a common practice. Unfortunately, the high performance of these voltage regulators caused a destabilizing phenomenon on the power system. Most of the problems are associated with the low frequency oscillation in interconnected power systems, especially in the deregulated paradigm. Small magnitude and low frequency oscillation often remained for a long time. To provide fast damping for the system and thus improve the dynamic performance, a[...]

Optimal placement and sizing of Static Var Compensators in power systems using Improved Harmony Search Algorithm

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This paper presents the application of the improved harmony search (IHS) algorithm for determining the optimal location and sizing of static Var compensator (SVC) to improve the voltage profile and reduce system power losses. A multi-criterion objective function comprising of both operational objectives and investment costs is considered. The results on the 57-bust test system showed that the IHS algorithm give lower power loss and better voltage improvement compared to the particle swarm optimization method in solving the SVC placement and sizing problem. Streszczenie. Artykuł przedstawia zastosowanie algorytmu IHS (Improved harmony search) do określania optymalnej lokalizacji kompensatora mocy biernej. Rezultaty testów wykazały że algorytm zapenia mniejsze straty mocy oraz zniekształcenia w porównaniu do innych metod optymalizacji. (Optymalizacja lokalizacji kompensatora mocy biernej z wykorzystaniem algorytmu IHS) Keywords: Static Var Compensator, Power Loss, Voltage Profile, Harmony Search Algorithm Słowa kluczowe: komensacja mocy biernej, algorytm HIS. Introduction Flexible AC transmission system (FACTS) can provide benefits in increasing system transmission capacity and power flow control flexibility and rapidity [1]. FACTS devices are power electronic converters that have the capability of controlling various electrical parameters in transmission circuits, facilities, both in steady state power flow and dynamic stability control. These devices include thyristor controlled series compensator, static Var compensator (SVC), unified power flow controller, static compensator (STATCOM), etc [2]. The most widely used shunt FACTS devices within power networks is the SVC due to its low cost and good performance in system enhancement. It is a shunt-connected static Var generator or absorber whose output is adjusted to exchange capacitive or inductive current so as to provide voltage support and when installed in a proper location, it [...]

Reliability Improvement in Distribution Systems by Optimal Placement of DSTATCOM Using Binary Gravitational Search Algorithm

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In this paper, a new method for improving reliability level of distribution systems is presented by employing optimal placement of DSTATCOM. The binary version of the Gravitational Search algorithm (BGSA) is used to solve the DSTATCOM optimal placement problem. The simulation results show that the proposed method is efficient and feasible for improving the system reliability level by reducing load outages and momentary interruptions. Streszczenie. Przedstawiono nową metodę poprawy niezawodności system dystrybucji energii dzięki optymalizacji DSTATCOM. Optymalne położenie DSTATCOM było określane na podstawie algorytmu BGSA. Uzyskano [poprawę dzięki dedukcji przerw w obciążeniu i chwilowych zaników. (Poprawa niezawodności systemu dystrybucji energii dzięki optymalnemu ustawieniu DSTATCOM) Keywords: Voltage sag, Reliability, Distribution Systems, DSTATCOM, GSA, Power Quality. Słowa kluczowe: niezawodność, system dystrybucji energii, DSTATCOM. Introduction The unprecedented changes in the technology have changed the customer’s expectation about quality and continuity of energy from power utilities. A minute disturbance such as voltage sag may cause large amount of financial loss due to increased level of dependency on electricity in industrial processes. Therefore, utilities have to consider seriously the quality and reliability of the power supply. Reliability is defined as the ability of a system to perform required functions under stated conditions for a given period of time. In power systems, reliability and security have the same implication. For example, a distribution system whose security level is low is said to be unreliable and vice versa. There are many reliability indices which are categorized in three groups, namely, sustained interruption indices, load based indices and momentary indices that are used for reliability assessment [1]. Among them, load based index such as the average system interruption frequency ind[...]

Heuristic Optimization Techniques to Determine Optimal Capacitor Placement and Sizing in Radial Distribution Networks: A Comprehensive Review

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Capacitors in power systems are used to supply reactive power to minimize loss and to improve the voltage profile. The appropriate placement of capacitors is also important to ensure that system power losses and total capacitor costs are minimal. The capacitor placement problem is commonly solved using heuristic optimization techniques which are diverse and have been the subject of ongoing enhancements. This paper presents a survey of the literature from the last decade that has focused on the various heuristic optimization techniques applied to determine optimal capacitor placement and size. Streszczenie. Kondensatory używane są w sieciach zasilających do poprawy jakości napięcia - zmniejszenia mocy biernej. Ważną rolę odgrywa umiejscowienie kondensatora. W artykule zaprezentowano przegląd literaturowy prac na temat metod optymalizacji umożlwiających określenia optymalnej pozycji I wielkości kondensatora. (Heurystyczne techniki optymalizacji umiejscowienia kondensatora w promieniowych sieciach zasilających - przegląd stanu wiedzy) Keywords: Capacitor Placement, Radial Distribution Network, Heuristic Optimization, Power System Harmonics. Słowa kluczowe: sieci zasilające, kondensator, zawartość 1. Introduction Shunt capacitors in distribution networks are used for various purposes: reducing power loss, improving the voltage profile along feeders, and increasing the maximum transmitted power in cables and transformers. To reduce power loss, shunt capacitors, which are commonly installed in power distribution networks, are used to compensate for reactive power. However, the installation of shunt capacitors in distribution networks requires consideration of their appropriate location and size. Capacitor placement is important to maximize loss reduction by properly installing shunt capacitors while minimizing shunt capacitor costs. Distribution networks are unbalanced due to mutual coupling between phase conductors and loading on the di[...]

Optimal Placement and Sizing of Shunt FACTS Devices in Power Systems Using Heuristic Optimization Techniques: a Comprehensive Survey

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The Static Var Compensator (SVC) and the Static Synchronous Compensator (STATCOM), as two components of Flexible AC Transmission System (FACTS) devices, play an important role in controlling the reactive power flow to the power network. Because of economic considerations, identifying the best location for installing the SVC and STATCOM is also important. The FACTS devices placement problem is commonly solved using heuristic optimization techniques which are diverse and have been the subject of ongoing enhancements. This paper presents a survey of the literature from the last decade that has focused on the various heuristic optimization techniques applied to determine optimal placement and sizing of the SVC and STATCOM. Streszczenie. W artykule analizuje się optymalne usytuaowanie elementów SVC I STATCOM w systemie FACTS. Przedstawiono stan wiedzy wykorzystania do tego celu różnych heurystycznych metod optymalizacji. (Optymalne usytuowanie elementów SVC i STATCOM w systemie FACTS) Keywords: Static Var Compensator (SVC), Static Synchronous Compensator (STATCOM), Heuristic Optimization, Placement, Sizing. Słowa kluczowe: SVC - statyczny kompensator mocy biernej, STATCOM - statyczny kompensator synchroniczny 1. Introduction Flexible AC Transmission Systems (FACTS) can provide benefits in increasing system transmission capacity and power flow control flexibility and speed [1]. FACTS devices are power electronic converters that have the capability to control various electrical parameters in transmission circuits and facilities, both in steady state power flow and dynamic stability control [2]. These devices include Thyristor Controlled Series Compensator (TCSC), Static Var Compensator (SVC), Unified Power Flow Controller (UPFC), Static Compensator (STATCOM), and others [3]. The SVC is the most widely used shunt FACTS device in power networks because of its low cost and good performance in system enhancement. It is a shuntconnected static[...]

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