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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
511

Modeling and simulation for signal and power integrity of electronic packages

Choi, Jae Young 06 November 2012 (has links)
The objective of this dissertation is to develop electrical modeling and co-simulation methodologies for signal and power integrity of package and board applications. The dissertation includes 1) the application of the finite element method to the optimization for decoupling capacitor selection and placement on a power delivery network (PDN), 2) the development of a PDN modeling method effective for multidimensional and multilayer geometries, 3) the analysis and modeling of return path discontinuities (RPDs), and 4) the implementation of the absorbing boundary condition for PDN modeling. The optimization technique for selection and placement of decoupling capacitors uses a genetic algorithm (GA) and the multilayer finite element method (MFEM), a PDN modeling method using FEM. The GA is customized for the decoupling problem to enhance the convergence speed of the optimization. The mathematical modifications necessary for the incorporation of the capacitor model into MFEM is also presented. The main contribution of this dissertation is the development of a new modeling method, the multilayer triangular element method (MTEM), for power/ground planes of a PDN. MTEM creates a surface mesh on each plane-pair using dual graphs; a non-uniform triangular mesh (Delaunay triangulation) and its orthogonal counterpart (Voronoi diagram), to which electromagnetic and equivalent circuit concepts are applied. The non-uniform triangulation is especially efficient for discretizing multidimensional and irregular geometries which are common in package and board PDNs. Moreover, MTEM generates a sparse, banded, and symmetric system matrix, which enables efficient computations. For a given plane-pair, MTEM extracts an equivalent circuit that is consistent with the physics-based planar-circuit model of a plane-pair. Thus, the values of the lumped elements can be simply calculated from the physical parameters, such as material properties and mesh geometries of each unit-cell. Consequently, the modeling of MTEM is flexible and easy to modify for further extensions, such as the incorporation of external circuits, e.g. decoupling capacitors and vertical interconnects. Power and ground planes provide paths for the return current of signal traces. Typically, planes have discontinuities such as via holes, plane cutouts, and split planes that disturb flow of signal return currents. At the discontinuity, return currents have to detour or switch to different layers, causing signal and power integrity problems. Therefore, a separate analysis of signal interconnects will neglect the significant coupling with a PDN, and the result will not be reliable. In this dissertation, the co-simulation of the signal and power integrity is presented focusing on the modeling of RPDs created by split planes, apertures, and vias. Plane resonance is one of the main sources of power integrity problems in package and board PDNs. A number of techniques have been developed and published in literature to reduce or prevent the resonance of a plane-pair. One of the techniques is to surround plane-pair edges with absorbing material that effectively damps the outgoing parallel-plate wave and minimizes the reflection. To model this behavior, the boundary condition of MTEM needs to be changed from its original form, the open-circuit boundary condition. In this dissertation, the application of the 1st order absorbing boundary condition to MTEM is presented.
512

A new proposed method of contingency ranking

Gossman, Stephanie Mizzell 18 May 2010 (has links)
Security analysis of a power system requires a process called contingency analysis that analyzes results from all possible single contingencies (i.e. outages) in the system. The process of contingency analysis requires the definition of a parameter that is used to monitor a certain aspect of the system, which is called a performance index. The performance index definitions used traditionally have been highly nonlinear, and the results have not accurately predicted the outcome of the performance index in some cases. These incorrect results are referred to as misrankings since the contingency results are usually placed in order of severity so that the most severe cases are evident. This thesis considers a new definition of contingency ranking using a more linearized definition of the performance index. The construction of both the new, proposed definition and the classic definition both consider the current loading of circuits in the system as compared to their rated values. Specifically, the parameter measured by the proposed definition measures the difference, while the more nonlinear definition uses a ratio of the two quantities, which is then raised to a higher power. A small, four bus test system is used to demonstrate the benefits of the new, more linearized definition. The average percent error for all single line contingencies of the system decreased by over 9.5% using the proposed definition as compared to the previous one. This decrease in error allows this performance index to monitor a similar parameter (comparing current loading and current rating of the lines) and achieve a higher degree of accuracy. Further linearization of this proposed definition also shows a reduction in the average percent error by an additional 22% so that when compared to the original, highly nonlinear definition, the average error is reduced by almost 30%. By linearizing the definition of the performance index, the results are more accurate and misrankings are less likely to occur from the security analysis process.
513

Direct AC control of grid assets

Sastry, Jyoti 20 May 2011 (has links)
The objective of the proposed research is to investigate feasible approaches to dynamic control of the power grid. Growth in the demand for electric power, and an increase in the penetration of renewable energy resources are causing congestion on an already aging power grid. Conventional grid control involves the use of static assets that operate on long time scales. These assets provide no dynamic control on the grid, and are typically used for scheduled support. Existing solutions (FACTS devices) to dynamic grid control have seen minimal market penetration because of high cost and low reliability. The proposed research provides a solution for dynamic control of the power grid that augments existing grid assets with a thin AC converter (TACC) to realize enhanced dynamic control. The TACC is a direct AC converter with filter elements and no bulk energy storage that dynamically reflects the asset value on the grid. The converter has a fail-normal mode of operation that returns the asset to its initial operating state, thereby not degrading system reliability. Some applications of TACCs include Inverter-Less STATCOMs and Controllable Network Transformers, which are realized by augmenting shunt VAR capacitors and load tap changers respectively. The principle of virtual quadrature sources is proposed to enable conditioning of AC voltages and currents. The concept is a novel method to realize control of phase angle and, or harmonics in single-phase AC converters, with no bulk energy storage. This concept is used to control the TACC and provides the asset with significantly enhanced control capabilities. Scaling of the TACC to utility voltage and power levels has been addressed by proposing a novel multilevel direct AC converter. The concept proposes the use of commercially available low cost semiconductor devices to realize high power converters. The specific application chosen to validate the concept of TACCs, through a medium voltage design, is the Inverter-less STATCOM.
514

A New Method To Determine Optimal Time-Delays Between Switching Of Digital VLSI Circuits To Minimize Power Supply Noise

Srinivasan, G 06 1900 (has links)
Power supply noise, which is the variation in the supply voltage across the on-die supply terminals of VLSI circuits, is a serious performance degrader in digital circuits and mixed analog-digital circuits. In digital VLSI systems, power supply noise causes timing errors such as delays, jitter, and false switching. In microprocessors, power supply noise reduces the maximum operating frequency (FMAX) of the CPU. In mixed analog-digital circuits, power supply noise manifests as the substrate noise and impairs the performance of the analog portion. The decrease in the available noise margin with the decrease in the feature size of transistors in CMOS systems makes the power supply noise a very serious issue, and demands new methods to reduce the power supply noise in sub-micron CMOS systems. In this thesis, we develop a new method to determine optimal time-delays between the switching of input/output (I/O) data buffers in digital VLSI systems that realizes maximum reduction of the power supply noise. We first discuss methods to characterize the distributed nature of the Power Delivery Network (PDN) in the frequency-domain. We then develop an analytical method to determine the optimal delays using the frequency-domain response of the PDN and the supply current spectrum of the buffer units. We explain the mechanism behind the cancellation of the power supply noise by the introduction of optimal buffer-to-buffer delays. We also develop a numerical method to determine the optimal delays and compare it with the analytical method. We illustrate the reduction in the power supply noise by applying the optimal time-delays determined using our methods to two examples of PDN. Our method has great potential to realize maximum reduction of power supply noise in digital VLSI circuits and substrate noise in mixed analog-digital VLSI circuits. Lower power supply noise translates into lower cost and improved performance of the circuit.
515

A technical analysis of distributed generation options for Tshwane electricity network.

Juma, Denis Wabwire. January 2011 (has links)
M. Tech. Electrical Engineering. / This study analyses the technologies with potential to generate this much needed power and transmit the electricity from the point of generation to the end use location. South Africa has abundant supplies of indigenous primary energy resources such as coal, wind, and solar. The global shift from regulation of electricity and other energy markets, community awareness of environmental impact caused by large conventional power plants, and advances in renewable and high efficiency technologies have led to greater interest in DG technologies based on Renewable Energy Sources (RES). In this study, DG based on renewable energy sources (wind, solar and energy from the waste) is considered. Their potential contribution within Tshwane is assessed.This research project presents a technical analysis of the Tshwane Electricity Network incorporating distributed renewable energy sources such as biomass, wind, solar and small-hydro. Their sizing and placement within the distribution systems is analysed in order to minimise the electrical network losses and to guarantee acceptable voltage profile. The optimisation process is a load flow based algorithm.
516

Μελέτη προβλήματος κατανεμημένης παραγωγής στα συστήματα ηλεκτρικής ενέργειας

Λάμπρου, Λάζαρος, Σταφυλιάς, Σπυρίδων 28 August 2009 (has links)
Σε αυτή τη διπλωματική εργασία διερευνούνται οι προδιαγραφές που πρέπει να ικανοποιούνται ώστε να είναι εφικτή η σύνδεση εγκαταστάσεων κατανεμημένης παραγωγής στα δίκτυα διανομής και η εφαρμογή τους σε ένα φωτοβολταϊκό σύστημα που συνδέεται στο δίκτυο χαμηλής τάσης. Στο πρώτο κεφάλαιο γίνεται μια επισκόπηση της παρούσας κατάστασης στην ηλεκτρική ενέργεια και αναλύονται οι λόγοι που οδήγησαν στην ανάπτυξη της κατανεμημένης παραγωγής οι οποίοι συνοψίζονται στους περιορισμούς στην κατασκευή νέων γραμμών μεταφοράς, στην αυξημένη ζήτηση παροχής ηλεκτρικής ενέργειας υψηλής αξιοπιστίας, στην απελευθέρωση της αγοράς ηλεκτρικής ενέργειας, στους προβληματισμούς για τις κλιματικές αλλαγές και στην εξάντληση των ορυκτών καυσίμων. Έπειτα αναλύεται ο ορισμός της κατανεμημένης παραγωγής σύμφωνα με τα διάφορα διεθνή ινστιτούτα ηλεκτρικής ενέργειας και αναπτύσσονται οι τεχνολογίες που περιλαμβάνει οι οποίες διαχωρίζονται σε τεχνολογίες φυσικού καυσίμου (fossil fuel technologies) και σε ανανεώσιμες πηγές ενέργειας. Στις πρώτες περιλαμβάνονται οι μηχανές εσωτερικής καύσης, οι αεριοστροβιλικοί σταθμοί, οι μικροστρόβιλοι ή μικροτουρμπίνες και οι σταθμοί συνδυασμένου κύκλου ενώ στις ανανεώσιμες πηγές ενέργειας περιλαμβάνονται οι ανεμογεννήτριες, τα κύτταρα καυσίμου (fuel cells), οι φωτοβολταϊκές γεννήτριες, τα μικρά υδροηλεκτρικά και οι μονάδες παραγωγής ηλεκτρικής ενέργειας από βιομάζα και φυσικό αέριο. Η λειτουργία ενός ηλεκτρικού δικτύου ελέγχεται από συσκευές προστασίας και ρύθµισης της τάσης, που έχουν σκοπό την παροχή προς τους καταναλωτές ηλεκτρικής ενέργειας αποδεκτής ποιότητας, ελαχιστοποιώντας τον αριθµό των σφαλµάτων και προσφέροντας υψηλό επίπεδο ασφάλειας. Η σύνδεση στο δίκτυο µονάδων κατανεμημένης παραγωγής πρέπει να συµβαδίζει µε αυτές τις γενικές αρχές, ώστε αφενός µεν να µην προκαλούνται ενοχλήσεις στους λοιπούς καταναλωτές και αφετέρου να υπάρχει συµβατότητα µεταξύ του δικτύου διανοµής και των εγκαταστάσεων των παραγωγών. Στο δεύτερο κεφάλαιο αναφέρονται οι προϋποθέσεις που πρέπει να ισχύουν για τη σύνδεση και παράλληλη λειτουργία των εγκαταστάσεων παραγωγής µε τα δίκτυα διανοµής, καθώς και ο απαιτούµενος εξοπλισµός ζεύξης και προστασίας, µε στόχο την αποτελεσµατική αντιµετώπιση της πλειονότητας των περιπτώσεων. Οι τεχνικές προδιαγραφές που περιγράφονται αφορούν στη σύνδεση παραγωγών στο δίκτυο µέσης τάσης (ΜΤ) ή χαµηλής τάσης (ΧΤ). Βασικά κριτήρια και προϋποθέσεις που εξετάζονται προκειµένου να επιτραπεί η σύνδεση νέων εγκαταστάσεων παραγωγής είναι η επάρκεια του δικτύου (γραμμών, μετασχηματιστών κλπ.), η συµβολή στη στάθµη βραχυκύκλωσης, οι αργές µεταβολές της τάσης (µόνιµης κατάστασης), οι ταχείες µεταβολές της τάσης, οι εκποµπές flicker, οι εκπομπές αρμονικών, η διαµόρφωση των προστασιών της διασύνδεσης εγκαταστάσεων-δικτύου και η επίπτωση στη λειτουργία συστηµάτων Τηλεχειρισµού Ακουστικής Συχνότητας (ΤΑΣ). Τα κριτήρια και οι µέθοδοι εξέτασης που περιγράφονται στηρίζονται κατά κύριο λόγο στη σειρά προτύπων 61000 της IEC (International Electrotechnical Commission) και εξασφαλίζουν την ικανοποίηση των απαιτήσεων του ευρωπαϊκού προτύπου ΕΝ 50160 (πρότυπο ΕΛΟΤ ΕΝ 50160 και Οδηγία διανοµής 120 της ΔΕΗ Α.Ε.). Στο τρίτο κεφάλαιο πραγματοποιείται μια μελέτη εφαρμογής των παραπάνω προδιαγραφών σε ένα σύστημα που εξομοιώθηκε με χρήση του προγράμματος PSCAD. Το σύστημα αποτελείται από μια φωτοβολταϊκή συστοιχία μέγιστης ισχύος 4,8 kW, έναν μετατροπέα συνεχούς/εναλλασσόμενης τάσης ή αντιστροφέα (DC to AC converter) που λειτουργεί με τη μέθοδο PWM (Pulse Width Modulation ή διαμόρφωση εύρους παλμού), ένα σύστημα παρακολούθησης του σημείου μέγιστης ισχύος που αποδίδει η συστοιχία (MPPT Maximum Power Point Tracker), ένα μετασχηματιστή 150V/380V για την ανύψωση της τάσης στην έξοδο του αντιστροφέα στα επίπεδα τάσης του δικτύου, ένα δίκτυο χαμηλής τάσης και δύο φορτία RL. Εκτενής αναφορά γίνεται στις εκπομπές αρμονικών που παρουσιάζονται στο σύστημα στην έξοδο του αντιστροφέα. Αρχικά γίνεται μελέτη χωρίς φίλτρο LC στην έξοδο του αντιστροφέα και στη συνέχεια παρατηρούμε τον τρόπο με τον οποίο το φίλτρο LC επιδρά στη μείωση των αρμονικών σε επιτρεπτά πλαίσια. Τέλος διερευνούνται οι διακυμάνσεις τάσης του δικτύου κατά τη ζεύξη του φωτοβολταϊκού συστήματος με το δίκτυο, πραγματοποιείται μια μελέτη του συστήματος σε περίπτωση βραχυκυκλωμάτων και διερευνάται η επίπτωση σε συστήματα τηλεχειρισμού ακουστικής συχνότητας. / -
517

An in-depth study into the various factors contributing to the unexplained line faults on a large high voltage network.

Bekker, H. J. J. January 2003 (has links)
The Eskom Transmission Network experiences an exceptionally high number of line faults, the cause of which, may not be correctly identified. This thesis analyses a number of all the possible factors responsible for causing these faults. The objective is to assign probable causes of these faults and that the correct preventative or corrective measures may be planned. The percentage of unexplained line faults is estimated to be 35 % of the total system faults. It is important for the Transmission Group of Eskom to minimise the number of faults. Major efforts to minimise identified faults such as bird streamers, veld fires, sugar cane fIfes, lightning and a hypothesised light pollution, light wetting mechanism has been undertaken by the transmission grid authority. This thesis presents an analysis of the statistical data of the unknown faults (unknown faults is defined as lines that trip due to a reason which could not be identified) that has been undertaken. This analysis takes into account a number of categories of causes of line faults. The period, for which the performance of the lines was analysed for was the years inclusive of 1993 to 1997. The investigation has focused on the identification of the under-performing lines of the main Transmission Network. The identified poorly performing lines have been compared with each other from the perspective ofthe following variables: • Region • Voltage (System Voltage) • Climatic Data Line faults - Time ofDay analysis • Line Faults - Time of Year analysis. The analysis indicates that the majority of unexplained flashovers occur between 22 :00 and 07:00 the following morning (Britten et al, 1999). Almost all of the under performing lines in South Africa fall in the sub-tropical/humid climatic area. All the lines studied are insulated with standard glass disc insulators. The analysis indicated that most of the unexplained line faults occur during the months when the seasons change, e.g. from autumn to winter. The analysis further indicates that most unexplained line faults occurred during the months of April to May and August to September. Of note is that during the period of this investigation bird guarding was performed on some lines. Installing bird guards may reduce those line faults that are caused by bird streamers. However, the bird pollution (deposited on glass disc insulators) that is not washed off at the same time as the bird guard installation may cause the line to trip due to the combination of the pollution and wetting resulting in a pollution type flashover. This is a possible cause of some unexplained line faults that occur from April to May. Bird streamers are also identified as the most probable cause of the unexplained faults which occur during the late evening periods (22:00 - 00:00). Pollution (with wetting) during the early morning periods may result in faults for the period 00:00 to 02:00. Line faults in the early morning periods (04:00 - 7:00) could be due to bird streamers or pollution and wetting, depending on the time of year in which the faults occurs. / Thesis (M.Sc.)-University of Natal, Durban, 2003.
518

An investigation into the present tariff cost structure and a methodology to determine the tariff increase for Ethekwini electricity.

Ramballee, Ashwin. January 2010 (has links)
EThekwini Electricity (EE) purchases its energy on the Megaflex tariff from Eskom which has had considerable changes in content over the years. This has caused the present tariffs offered by EE to move away from cost reflectivity. Structural changes over the years have caused distortion to even the supposedly cost reflect ‘Time of Use’ tariff (TOU) which emulated Eskom’s previous Large Power Users (LPU) tariffs. The divergence between the purchase of electricity and the method of recovery for the sales becomes a cause for concern. This opens EE to risk of not being able to offer cost reflective tariffs and diminish risks in recovery via the tariffs. This has an impact on the budgeted revenue. The primary intention of this study was to establish a formalised procedure and to develop a methodology that Ethekwini Electricity (EE) can use for the review of their tariffs. This study was necessary and extremely crucial for the mitigation of financial risk when tariffs are reviewed and restructured since the revenue recovered via the tariffs are in excess of 5 billion rand per annum. The study consisted of the development of a methodology which consists of a process flowchart and a series of Excel spreadsheets in which the analysis was done. The development of the model utilised information that were readily available and data that were extracted and manipulated from installed systems. The objectives were to determine all associated costs for the delivery of electricity, identify cost drivers, determine cost structure and finally determine applicable tariffs for EE. Issues such as customer categorisation, cross subsidisation, cost reflectivity and affordability were taken into account. This model could now be used in the future for tariff increases and applications to the regulator. This methodology was used to design of the 2009/2010 electricity tariffs for Ethekwini Electricity. The outcome of this study resulted in the re-categorisation of EE’s customer base, changes to the tariff structures and the phasing out of the non cost reflective tariffs. This study enabled the restructure of the LPU TOU tariff which was crucial for EE’s cost recovery. It also resulted in the development of two new TOU tariffs for residential and commercial customers. Whilst other municipalities experienced difficulties in recovering their revenue due to Eskom’s restructured Megaflex tariff, EE’s actual revenue differed by 1% when it was compared to the budgeted revenue towards the end of 2009. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.
519

Increasing distributed generation penetration when limited by voltage regulation

Nye, Jonathan Mark 04 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This work investigated the influence of photo-voltaic generators on the voltage control of distribution feeders and the methods that can be used to increase the maximum penetration levels of these feeders. Initially, a brief overview of the reasons why it is necessary to increase the generation penetration levels on distribution feeders was provided. A review of various issues associated with connecting generation to the distribution network; methods and technologies that can be used to increase penetration levels; and ways to improve voltage regulation on MV feeders was given. The grid code for renewable power plants and the voltage apportionment standard were reviewed to determine what limits penetration levels and what can be done to increase them. The operation and control of a typical distribution network, without any connected generation, was initially investigated. A control strategy was implemented that provided suitable voltage regulation on the feeder during both high and low load. The influence of connecting generation to this typical distribution network, without making any modifications to the control of the feeder, was investigated. Base penetration levels, for various generation connection cases, were found. It was shown that the penetration is limited by the rapid voltage change or voltage rise. The base penetration levels were compared to the optimal amount of generation that provides the lowest losses. It was shown that the penetration needs to be increased by between 100% and 200% for the feeder’s losses to be minimised. Voltage regulator and capacitor control was influenced by the generation and they could not function as expected. It was shown that flicker will not be an issue, even with penetration limits well above the current allowable limits. Various methods that can be used to increase the amount of generation that is connected to the typical network were investigated. On-load tap changer setpoint reduction, reactive power control and electronic voltage regulators are some of the methods or technologies that can be used to increase penetration levels. It was shown that each of the technologies can assist, depending on the circumstance, in increasing penetration. The individual modifications can increase penetration up to 100% at the cost of increased tap changes and in some cases losses. Two proposed control strategies were assessed, that combine the investigated technologies. The results showed that it is possible to increase penetration levels by 50-80%, while improving power quality and reducing losses when compared to the base generation connection case. / AFRIKAANSE OPSOMMING: Hierdie werk ondersoek die invloed van die foto- voltaïes kragopwekkers op die spanning beheer van die verspreiding voerder asook die metodes wat gebruik kan word om die maksimum penetrasie vlakke van hierdie voerders te verhoog. Aanvanklik is 'n kort oorsig van die redes waarom dit nodig is om die opwekking penetrasie vlakke op die verspreiding voerders, te verhoog voorsien . Eerstens word 'n hersiening van verskeie kwessies wat verband hou met die koppeling van generasie na die verspreidingsnetwerk gegee. Tweedens word metodes en tegnologie wat gebruik kan word om penetrasie te verhoog gegee en laastens word maniere om spanning regulasie op medium spanning voerders te verbeter, gegee. Die rooster kode "grid code => probeer liewer netwerk regulasies" vir hernubare krag aanlegte en die spanning toedeling standaard is hersien om te bepaal wat beperk die penetrasie vlakke en wat gedoen kan word om dit te verhoog. Die werking en beheer van 'n tipiese verspreiding netwerk, sonder enige verbonde generasie, is aanvanklik ondersoek. 'n Beheer-strategie is toe geïmplementeer wat geskikte spanning regulasie op die voerder tydens beide hoë en lae belasting verskaf. Die invloed van die koppeling van opwekking tot hierdie tipiese verspreiding netwerk, sonder om enige veranderinge aan die beheer van die voerder, is ondersoek. Basis penetrasie vlakke, vir verskeie generasie verband gevalle, is gevind. Daar is bewys dat die penetrasie word beperk deur die vinnige spanning verandering of spanning styging. Die basis penetrasie vlakke word vergelyking met die optimale aantal generasie wat die laagste verliese bied. Daar is bewys dat die penetrasie moet met tussen 100% en 200% verhoog word sodat die voerder se verliese beperk kan word. Die spanning reguleerder en kapasitor beheer is beïnvloed deur die opwekking en hulle kon nie reageer soos verwag nie. Daar is getoon dat flikker nie 'n probleem sal wees nie; selfs al is die penetrasie vlakke ver bo die huidige toelaatbare grense. Verskillende metodes wat gebruik kan word om die aantal generasie wat gekoppel is aan die tipiese netwerk te verhoog is ondersoek. Aan-las tap wisselaar vermindering, reaktiewe krag beheer en elektroniese spanning reguleerders is 'n paar van die tegnieke wat gebruik kan word om penetrasie te verhoog. Daar is bewys dat elkeen van die tegnologieë kan help, afhangende van die omstandighede, vir toenemende penetrasie. Die individuele veranderinge kan penetrasie verhoog tot 100% by die koste van 'n verhoogde tap veranderinge en in sommige gevalle verliese. Twee voorgestelde beheer strategieë is beoordeel, wat die ondersoek tegnologie kombineer. Die resultate het getoon dat dit moontlik is om penetrasie te verhoog met 50% tot 80%, terwyl die verbetering van gehalte en die vermindering van krag verliese in vergelyking met die basis generasie verband hou.
520

Distributed series reactance: a new approach to realize grid power flow control

Johal, Harjeet 17 November 2008 (has links)
The objective of the proposed research is to develop a cost-effective power flow controller to improve the utilization and reliability of the existing transmission, sub-transmission, and distribution networks. Over the last two decades, electricity consumption and generation have continually grown at an annual rate of around 2.5%. At the same time, investments in the Transmission and Distribution (T&D) infrastructure have steadily declined. Further, it has become increasingly difficult and expensive to build new power lines. As a result, the aging power-grid has become congested and is under stress, resulting in compromised reliability and higher energy costs. In such an environment it becomes important that existing assets are used effectively to achieve highest efficiency. System reliability is sacrosanct and cannot be compromised. Utility system planners are moving from radial towards networked systems to achieve higher reliability, especially under contingency conditions. While enhancing reliability, this has degraded the controllability of the network, as current flow along individual lines can no longer be controlled. The transfer capacity of the system gets limited by the first line that reaches the thermal capacity, even when majority of the lines are operating at a fraction of their capacity. The utilization of the system gets further degraded as the lines are operated with spare capacity to sustain overloads under contingencies. Market efficiency is also sub-optimal, with congestion on key corridors restricting the low-cost generators to connect to the end users, resulting in higher electricity prices for the consumers. The proposed technology offers the capability to realize a controllable meshed-network, with the ability to utilize static and dynamic capacity of the grid to provide system-wide benefits, including- increased line and system-capacity utilization, increased reliability, improved operation under contingencies, and rapid implementation. It would allow a broadening of the energy market, permitting owners to direct how energy flows on their wires, and making it easier to connect to new sources of generation.

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