To see the other types of publications on this topic, follow the link: Electric power supply.
Dissertations / Theses on the topic 'Electric power supply'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Electric power supply.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Zitouni, Salah. "An expert system for electric power system management." Thesis, University of Dundee, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338200.
Full text
2
Lao, Keng Weng. "A novel electric traction power supply system using hybrid parallel power quality compensator." Thesis, University of Macau, 2011. http://umaclib3.umac.mo/record=b2550461.
Full text
3
Camacho, Rojas Jorge Arturo. "Distributing power : a cratological study of emerging technologies for electric power supply." Thesis, University of East London, 2010. http://roar.uel.ac.uk/2601/.
Full textAbstract:
This thesis has two main objectives. First, to develop a philosophical and theoretical framework for a cratological (from the Greek kratos: power) study of technology, i.e. one that explains and evaluates how certain technologies afford states or changes in the structure of power of the social systems in which they are embedded. The normative principle proposed is the ideal of equality of power. The second objective is to deploy these frameworks in an analysis of the technological and industrial development of systems for electric power supply. Driven by a quest to achieve greater economies of scale, the technological development of the industry during the 20th century emphasised constant increments in output scale and a model of centralised supply. Along with this process came a configuration and consolidation of the industry around a highly concentrated or monopolistic structure. In these conditions, utilities and other power companies acquired control over a key social resource, namely electric energy, and a concomitant share of social power. Since the 1980s, but particularly in the last decade, technological innovations are opening the possibility of a radical transformation in the industrial structure of power supply systems around the paradigm of distributed energy resources. Along with important technical, economic and ecological benefits, this new paradigm may afford a positive, from our cratological perspective, transformation: namely a shifting of control over the electricity supply system towards communities, small and independent generators, and a new breed of energy prosumers. All of these may find themselves newly empowered by the emerging technological paradigm, in a way that is similar to what is also becoming possible in the communications industry thanks to the development of the Internet.
4
Smyth, Thomas Paton. "A review of the emergency electric power supply systems at PWR nuclear power plants." Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/22430.
Full textAbstract:
Bibliography: pages 168-174.The Emergency Electric Power Supply Systems at Pressurized Water Reactor Nuclear Power Plants are reviewed, problem areas are identified, and recommendations are made for existing and future Nuclear Power Plants. A simplified introduction to a typical Pressurized Water Nuclear Reactor is given and the problems associated with the commercial use of nuclear power are discussed. An overview of the Nuclear industry's solutions is presented and covers the Reliability of equipment and the American Regulatory requirements. The alternating and direct current power supply systems are examined in terms of plant operational state and equipment type (Diesel generators, Grid network, Lead-acid batteries, Battery chargers, Inverters, and Power Distribution networks). The trends in the design of Emergency Electric Power supply systems at Nuclear Power Plants are presented. The loss of all alternating current power, known as Station Blackout, is discussed and the American and European response to this. problem is presented. Problems experienced in the direct current systems are discussed and solutions are presented. The experience at Koeberg Nuclear Power station with Lead-acid batteries is included in the discussion. The thesis concludes with recommendations for designers and operators of the Electric Power Supply Systems at Nuclear Power Stations.
5
Commin, Andrew Neil. "Matching renewable electricity supply to electricity demand in Scotland." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=230176.
Full textAbstract:
The threat of climate change has led to many countries and regions adopting renewable targets. Scotland's is one of the most ambitious, with an aim to generate the equivalent to 100% of its electricity needs from renewable sources by 2020. Scotland has a very large renewable resource, primarily consisting of offshore and onshore wind, tidal stream, wave and hydro power; all of which are characterised by having variable output. Over a long period, such as a year, variability in renewable generation will average out and may meet or exceed total annual demand. This thesis investigates whether matching of demand and generation is possible within a timescale meaningful to electricity system users; that is whether renewable generation can meet electricity demand in any given hour. This was established by using historic data to create an hourly generation hindcast of Scotland's renewable generation over a 30 year climate “normal” period. These outputs are then compared to a hindcast of hourly demand based on observations over the most recent few years. The results demonstrated that it is possible for Scotland to rely entirely upon renewable generation to fulfil demand in any hour of the 30 year hindcast. However, it appears that the renewable capacity and storage currently built or within the Scottish planning system is only sufficient to match demand in 65% of the hours within the hindcast. The hindcast allows judgements to be made as to how 100% of demand could be met most effectively and provides the basis of a coherent planning strategy, with security of supply at its centre. Further wave and tidal stream capacity is shown to be of higher value than additional wind power but in the latter case, addressing the geographical diversity of wind power can enable maximise phasing between sites to increase the security of supply. Importantly this work provides a means of informing decision making about where best to develop wind, wave and tidal resources and what additional storage may be required in order to provide 100% security of supply. The results are also of particular importance to Scotland's renewable generation strategy in the case of assessing where new on- and off-shore wind farms should be developed, as wind is set to dominate Scotland's renewable portfolio for the foreseeable future.
6
Parikh, Rajiv D. "PC based simulation software package for an uninterruptable power supply." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-11242009-020238/.
Full text
7
Lee, Kelvin. "A study of supply function equilibria in electricity markets /." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112573.
Full textAbstract:
Deregulation is a growing trend and the electricity industry has not escaped its reaches. With worldwide experiences spanning only thirty years, there is substantial interest in analyzing current and future market designs so that market power cannot be used to increase the price of electricity significantly.This thesis analyzes market power in electricity markets through the notion of Nash equilibrium (NE) and, more specifically, through Supply Function Equilibrium (SFE). We will examine how SFE can be modified to incorporate capacity constraints on generators and generating companies (gencos) controlling more than one generator for a Poolco electricity market with marginal pricing.
A genco's supply function is assumed to be of the form gi=l-aibi . Gaming is done either with ai or bi only, while keeping the other parameter at true cost. Gaming with both variables cannot be analyzed since the problem would have too many degrees of freedom. For each possible generator output level (minimum output, maximum output, or in between), analytical methods are employed to determine all candidate Nash equilibria. Then, simulations are performed over the range of possible genco offers to determine whether these candidates meet the complete set of Nash equilibrium criteria, specifically whether any genco can or cannot improve its profit by gaming.
For various inelastic demand levels, study cases indicate that there are either no Nash equilibria or only one. In the multi-unit genco case, the price of electricity is found to be higher than in the case where each genco owns only one generator, illustrating the effect of market concentration on the price. Whether capacity constraints are considered or not, the price of electricity appears to be higher if gencos are allowed to game with bi instead of ai.
The inclusion of capacity constraints on generators and the consideration of the multi-unit genco case will allow for better genco modeling in a Poolco market with marginal pricing. In turn, this will lead to more accurate analysis of the effects of current and possible rules and regulations on the price of electricity.
8
Patel, Amit P. "High power-supply rejection current-mode low-dropout linear regulator." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28115.
Full textAbstract:
Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Rincón-Mora, Gabriel; Committee Member: Ghovanloo, Maysam; Committee Member: Leach, W. Marshall.
9
Ghasemzadeh, H. R. "The power supply and automatic control of a mains electric tractor." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383690.
Full text
10
Grenier, Jason. "Design of a MOSFET-Based Pulsed Power Supply for Electroporation." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/844.
Full textAbstract:
The use of high-voltage pulsed electric fields in biotechnology and medicine has lead to new methods of cancer treatment, gene therapy, drug delivery, and non-thermal inactivation of microorganisms. Regardless of the application, the objective is to open pores in the cell membrane and hence either facilitate the delivery of foreign materials inside the cell or to kill the cell completely. Pulsed power supplies are needed for electroporation, which is the process of applying pulsed electric fields to biological cells to induce a temporary permeability in the cell membrane. The applications of pulsed electric fields are dependent on the output pulse shape and pulse parameters, both of which can be affected by the circuit parameters of the pulsed power supply and the conductivity of the media being treated. In this research, two Metal Oxide Field Effect Transistor (MOSFET)-based pulsed power supplies that are used for electroporation experiments were designed and built. The first used up to three MOSFETs in parallel to deliver high voltage pulses to highly conductive loads. To produce pulses with higher voltages, a second pulsed power supply using two MOSFETs connected in series was designed and built. The parallel and series MOSFET-based pulsed power supplies are capable of producing controllable square pulses with widths of a few hundred nanoseconds to dc and amplitudes up to 1500 V and 3000 V, respectively. The load in this study is a 1-mm electroporation cuvette filled with a buffer solution that is varied in conductivity from 0. 7 mS/m to 1000 mS/m. The results indicate that by controlling the circuit parameters such as the number of parallel MOSFETs, gate resistance, energy storage capacitance, and the parameters of the MOSFET driver gating pulses, the output pulse parameters can be made almost independent of the load conductivity.
Using the pulsed power supplies designed in this work, an investigation into electroporation-mediated delivery of a plasmid DNA molecule into the pathogenic bacterium E. coli O157:H7, was conducted. It was concluded that increasing the electric field strength and pulse amplitude resulted in an increase in the number of transformants. However, increasing the number of pulses had the effect of reducing the number of transformants. In all of the experiments the number of cells that were inactivated by the exposure to the pulsed electric field was measured.
11
Sharam, Andrea. "Market segmentation and domestic electricity supply in Victoria." Swinburne Research Bank, 2005. http://adt.lib.swin.edu.au/public/adt-VSWT20061109.101315.
Full textAbstract:
Thesis (PhD) - Institute for Social Research, Swinburne University of Technology, 2005.Thesis submitted in fulfillment of the requirements of the degree of Doctor of Philosophy, Institute for Social Research, Swinburne University of Technology, 2005. Typescript. Bibliography: p. 188-207.
12
Jacobs, D. M. (Danver Maxwill). "Voltage control of medium to high power three-phase inverter supply systems." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52608.
Full textAbstract:
Thesis (MScEng)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: In this thesis a new voltage control method is developed for a three-phase inverter supply system. The inverter supply system consist of a Permanent Magnet Generator, a three-phase rectifier, a three-phase inverter plus LC-filter and a three-phase transformer in series. This system supplies power to a network or to a stand-alone load. The main focus of this thesis is on the control aspects of the inverter and the LC-filter. Different voltage control systems are investigated and compared to each other. From these methods the proposed voltage control method is developed where only the output voltages are measured to establish good voltage control. All these voltage control methods are also simulated with a software package. The proposed voltage control method compares very well with other voltage control methods. The results that are obtained in the simulations are satisfactory. The proposed voltage control method is also implemented in an 8 kW laboratory scale model and, again, very good practical results are obtained. A TMS320F240 nsp controller is used to implement the proposed voltage control method. The controller compensates well for load steps, and these results compare well to an alternative voltage control method, which was also evaluated practically.
AFRIKAANSE OPSOMMING: In hierdie tesis IS 'n nuwe spanningsbeheermetode ontwikkel VIr 'n drie-fase wisselrigter kragtoevoerstelsel. Die wisselrigter kragtoevoerstelsel bestaan uit 'n Permanent Magneet Generator, 'n drie-fase gelykrigter, 'n drie-fase wisselrigter plus Le-filter, en 'n drie-fase transformator in serie. Hierdie stelsel voorsien krag aan 'n netwerk sowel as aan 'n alleenstaande las. Die hooffokus van hierdie tesis is op die beheeraspekte van die wisselrigter en Le-filter. Verskillende spanningsbeheermetodes is deeglik ondersoek en vergelyk met mekaar. Uit hierdie metodes is dan die voorgestelde beheermetode ontwikkel waar slegs die uittreespanning gemeet word om goeie spanningsbeheer te kan doen. Al hierdie spanningsbeheermetodes is dan gesimuleer met 'n sagteware pakket. Die voorgestelde spanningsbeheermetode vergelyk baie goed met die ander spanningsbeheermetodes. Die resultate verky in die simulasies is ook baie bevredigend. Die voorgestelde beheermetode is ook geïmplementeer op 'n 8 kW laboratorium skaalmodel en weereens is baie goeie praktiese resultate verky. 'n TMS320F240 DSP-beheerder is gebruik om die voorgestelde beheermetode mee te implementeer. Die beheerder kompenseer baie goed vir lastrappe en vergelyk ook goed met 'n ander spanningsbeheermetode wat prakties ge-evalueer is.
13
Steyn, Grove. "Governance, finance and investment : decision making and risk in the electric power sector." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390926.
Full text
14
Tambatamba, Terence. "Improvement of power supply reliability : Case Study: Zambia." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9854.
Full textAbstract:
This thesis studied reliability of power supply in Zambia following two major power blackouts that affected the whole country. The case study focussed on the generation and transmission network owned by Zambias biggest utility company Zesco. Three methods of study were selected. The first method looked at the transient stability simulations of Zesco generators when subjected to a large disturbance after a three phase short circuit was applied at three selected buses which are considered critical to the system. The simulations were carried out in SIMPOW. The results show that with fault duration of less than 200 milliseconds, all generators regained synchronism after fault removal. However, extending the fault duration to 200 milliseconds resulted in loss of synchronism in generators at Victoria Falls power station. The second method studied the contingency of some critical components in the Zesco system. The contingency analysis was implemented using software called NETBAS. Study showed that the Zesco system is N-1 stable for contingencies involving transmission lines and transformers. However the system is vulnerable to contingencies involving major power stations such as Kafue gorge and Kariba North bank. The third study proposed modification to the distance protection system to include the effect of zero sequence mutual coupling resulting from parallel circuits following a fault involving earth on a protected line. Adaptive techniques were developed where the settings of the distance relay would change to suit the circuit configuration. This technique resulted in optimal performance of the distance relay under all conditions of parallel line operation. The thesis concludes by making recommendations based on the findings from the studies carried out.
15
Kaya, Ibrahim. "A Switch Mode Power Supply For Producing Half Wave Sine Output." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609781/index.pdf.
Full textAbstract:
In this thesisanalysis, design and implementation of a DC-DC converter with active clamp forward topology is presented. The main objective of this thesis is generating a rectified sinusoidal voltage at the output of the converter. This is accomplished by changing the reference signal of the converter. The converter output is applied to an inverter circuit in order to obtain sinusoidal waveform. The zero crossing points of the converter is detected and the inverter drive signals are generated in order to obtain sinusoidal waveform from the output of the converter. Next, the operation of the DC-DC converter and sinusoidal output inverter coupled performance is investigated with resistive and inductive loads to find out how the proposed topology performs. The design is implemented with an experimental set-up and steady state and dynamic performance of the designed power supply is tested. Finally an evaluation of how better performance can be obtained from this kind of arrangement to obtain a sinusoidal output inverted is thoroughly discussed
16
Tsang, Siu-hing. "Research on the electricity supply and demand relationship in China and the development strategy to 2020 /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19874613.
Full text
17
Ferdoush, Md Asif. "System Stability of the Overhead Power Supply System used in the Electric Road System." Thesis, Scania CV AB, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-399815.
Full textAbstract:
This thesis presents the stability analysis of an Electric Road System (ERS), which is often abbreviated as eHighway, used for the electrification of the hybrid vehicle. The overall system modelling of the ERS, starting from the sub-station to the critical part of the Scania hybrid truck is performed in the MATLAB Simulink environment. The ERS consists of an overhead catenary line (OCL), where vehicles are electrified by using a pantograph mounted over the vehicle. The stability analysis of the power supply of the overhead line is done by taking into account several aspects of the system. The simulation results are validated with the real test track measurements and the deviations are shown. The frequency response of the system is considered to measure the stability margin. The resonance conditions are clarified and essential variable choke is proposed to damp them out. Also the harmonic components injected from the vehicle side, that are in the closer range of the resonance, are figured out and filtered. When multiple vehicles are electrified from the same catenary line, then there are interferences in between the vehicles. These disturbances both to the vehicles and the overhead power supply system are presented in the time domain. Finally, the results are shown to demonstrate the effectiveness of the variable choke to increase the stability margin in the overhead supply system. In the frequency domain results, it has shown that the resonance is shifted out of the system operating frequency. In the time domain results, it has shown that the high amplitude of the current and voltage signals are sufficiently damped out by variable choke implementation.
18
Gezgin, Cahit. "Simultaneous control-structure optimization of power converters." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15796.
Full text
19
Momen, Mustafa. "Long-term supply mix planning of power systems accounting for greenhouse gas emissions." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115996.
Full textAbstract:
Recent scientific findings have generated considerable concern about the adverse effect of greenhouse gas (GHG) emissions on the world's climate in general and global warming in particular. In Canada and many other countries, this concern has led to the adoption of legal and political steps with the aim of curbing GHG emissions. The first part of this thesis describes the steps taken by Canada in this regard.Such steps provide a strong incentive to Canadian power systems to incorporate reduction of GHG emissions in their planning process. Thus, in the second part of the thesis, a long-term supply mix planning model is developed. Since significant decrease in GHG emissions is unlikely to occur without removal of highly polluting power plants, this model allows for decommissioning these power plants.
Finally, the supply mix planning model is applied to evaluate the strategy of joint planning (as opposed to separate planning) of the power systems of Quebec and Ontario. Results obtained from the model leads to the conclusion that joint planning is preferable from the point of view of overall social and financial cost.
20
Jooste, Kritzman Phillip. "A load management system for fixed appliances in a safe DC RDP house." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2634.
Full textAbstract:
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017.This dissertation represents the design and development of a load management system for fixed appliances in a safe direct current (DC) Reconstruction and Development Programme (RDP) house. A combination of valley filling, load shifting and peak clipping load management techniques were employed to assist in reducing the peaks observed in the RDP house load profile during peak hours. A DC RDP house laboratory model was developed. The study is based on the assumption that the normally 220 V alternative current (AC) grid is replaced by a 350 V DC grid. The assumption is thus that 350 V DC is available at the distribution box in the RDP house laboratory model. All theoretical work was based on a 350 V DC system, but due to the lack of a laboratory 350 V DC supply, all physical tests were conducted by making use of a 300 V DC supply which was available. Consequently all calculations were thus based on 300 V DC as well. The geyser was the main fixed appliance focused on since it contributes to a significant portion of the power used. An AC geyser was successfully modified in order to be used in the DC network. Safety of the system was considered in order to interrupt the power in case of overcurrent or to isolate the power. Electronic switches were also developed and implemented to ensure that the DC power could be safely switched on and off and that the low power DC was isolated from the high power DC. LabVIEW allowed all other appliances in the DC RDP house to be virtually represented so that a holistic view of the power use of the house could be represented. This also allowed the system to be successfully simulated before any physical work was conducted. The load management system was successfully implemented by making use of power line communication. This proved to be a cost effective means to apply the load management algorithm. The algorithm consisted mainly of power on / off instructions that were executed during peak and off-peak times. It follows the normal use of timers used in the AC system to help reduce demand. It was found that the load management system successfully reduced the demand during peak hours without compromising the basic needs of the user. The power line communication modem proved to be very reliable in implementing the load management algorithm.
21
Sharam, Andrea, and n/a. "Market segementation and domestic electricity supply in Victoria." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20061109.101315.
Full textAbstract:
If the observations of unregulated and recently deregulated essential services were to hold
for electricity reform, we could expect to see market segmentation of household
customers. This is a corporate strategy aimed at the acquisition of attractive customers
and the avoidance of unattractive customers. It is a function of market relations and
commodification. Some markets already segment and assign unattractive customers to
'residual' markets, 'sub-prime' markets or 'markets of last resort'. Residual markets tend to
involve market abuse by suppliers because these customers lack market power. It is
possible therefore to suggest that segmented markets are characterised by simultaneous
competition and monopoly. The implications for the supply of essential services, such as
electricity, are profound. This research sought to identify whether there is evidence of
emerging segmentation of the domestic electricity market in Victoria.
In practice, few essential services areas are completely deregulated. The history of
segmentation in the US insurance and lending industries provides valuable insights into
markets, market failure and social protections. Taking this history and the more recent
experiences of reforms in the US, the UK and Australia, it has been possible to identify
three models of social protection: 'universal service', a 'civil rights' model, and a 'market'
model. The Victorian reforms reflect some elements of each of these. The social
protections included in the reform package both encourage and present barriers to market
segmentation. At the time of the research, some elements of the safety net arrangements
and customer inertia (born out of negative attitudes to competition) have acted to inhibit
segmentation. Customer inertia in its own right poses questions for the efficacy of
competition policy.
The key understanding that is gained from this research is that both civil rights and socioeconomic
entitlements (social rights) are required to prevent markets in essential services
acting upon and exacerbating inequality. This suggests that universal service, as a model
of social protection, is most likely to ameliorate the impacts of inequality.
22
Abbanat, Cherie Miot. "The impact of deregulation of the electric supply industry on renewable power generation projects." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10501.
Full text
23
Javanshir, Marjan. "DC distribution system for data center." Thesis, Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39344952.
Full text
24
Tan, Pee-Chin 1975. "A VSI-based power quality conditioner for 25kV electrified railway systems." Monash University, Dept. of Electrical and Computer Systems Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5537.
Full text
25
Aminou, Moussavou Anges Akim. "Modelling and analysis of microgrid control techniques for grid stabilisation." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1184.
Full textAbstract:
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the
Cape Peninsula University of Technology
2014In recent times, renewable energy-based distributed generation (DG) has captivated the industrial sector and on a global scale this has become a leading research area. Distributed generation using wind, solar energy or biomass as a source of energy can produce electricity on a small scale. Therefore, there is a strong focus on using renewable energy as a safe alternative source of energy, especially because it can in future play a dominant role in the world’s energy production and help to tackle the increase of global warming caused by fossil energy. However, a major problem facing renewable energies is that they are highly dependent on weather conditions. Since the power generated by DG, as well as consumption, depends on the weather conditions, irregularity of production and consumption leads to frequency and voltage fluctuations, and it can become difficult to determine and monitor consumer usage at any given time. Distributed generation can then be subjected to discrepancies in consumer usage and this can lead to severe overloading. As a result, microgrids powered by DG, operating in a single, stand-alone controllable system mode, face new challenges in terms of balancing a cluster of loads. Balancing a cluster of loads by making sure at all times that the entire system operates without overloading, is an essential requirement for the proper operation of a power system. The microgrid load considered in this project is the sum of sensitive and non-sensitive loads, respectively 5 kW and 100 kW, which constitute load requirement of one village; this total load required by a number of villages is called a cluster load. Depending on the input power generated by a DG-based photovoltaic (PV) system, these loads can be controlled using a logic control switch (LCS). When the power produced is less than the minimum load required by a component of a cluster, overloading occurs. The purpose of using an LCS is to ensure that a stable system is maintained under various loads and resource conditions. An LCS is used to continuously monitor and adjust load through circuit breakers. It is a good alternative to load balancing for a cluster of villages in rural area where a microgrid is operating in stand-alone mode. The focus of this research is to design a photovoltaic system with a maximum capacity of 1 MW providing power to a cluster of rural villages, and operating in stand-alone mode, and then to apply different control techniques (droop control, dq0 reference frame + proportional integral (PI) controller, and PI controller alone) at the inverter terminal of the PV system, in order to evaluate the stability of the output voltage. Another goal of the research is to develop an energy management system (EMS) algorithm to support the PV system in reducing loads. Therefore, a iii stable system under various load and resource conditions, as well as suitable control mechanisms are required to model a PV system. There is a need for the modelling of a PV array using a physical modelling block in MATLAB (SIMULINK) software. The state flow provided by SIMULINK is used in this project to develop an algorithm for load balancing. The state flow gives possibilities of modelling complex algorithms by combining graphical and tabular representations to create sequential decision logic, derived from state transition diagrams and tables, flow charts and truth tables. Furthermore, the design of a microgrid using photovoltaic DG and an energy management system, has been developed. The present work mainly consists of a stand-alone microgrid operation, where the power generated must be equal to the load power. In addition, different control methods, consisting of a dq0 reference frame + PI controller, are analysed at the invertor terminal. Subsequently an LCS algorithm is developed; this is required to maintain the system within certain limits and prevents overloading. LCS algorithms are based on a flowchart and allow switching automatically selected loads, depending on the power (solar radiation) available. In addition, a flow chart provides an easy way of using a graphical transition state and state chart to establish a set of rules for the system. The simulation results show that both droop control and a dq0 reference frame + PI controller are much better than a PI controller alone; these results also compared well with similar studies found in the literature. Also, these results are further improved with an EMS in order to maintain the output voltage of the microgrid, by switching on and off certain loads depending on the input power. The modelling of the microgrid using DG, based on photovoltaic systems with a maximum capacity of 1 MW, supports and improves the PV system by reducing loads. Moreover, droop control, and dq0 transformation + PI control present a better result than PI controller alone.
26
曾紹興 and Siu-hing Tsang. "Research on the electricity supply and demand relationship in China and the development strategy to 2020." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31269321.
Full text
27
Petersen, Mervyn. "Improving outage process maturity level using a process maturity model." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2561.
Full textAbstract:
Thesis (MTech (Quality (Engineering)))--Cape Peninsula University of Technology, 2016.The research study establishes the maturity level of the outage process of the Outage Management Department at Eskom. The outage process started in 2012 to contribute to the effective planning and execution of outages. The successful completion of outages depends on effective planning and execution of an outage. At the time of the research study, poor outage performance at Eskom’s power stations contributed to load shedding of electricity in South Africa. The research problem statement reads as follows: The absence of an outage process maturity indicator diminishes the ability of the Outage Management Department (OMD) to comprehend the current process maturity level. The research question: Will the Outage Management Department be able to identify improvement opportunities if the maturity level of the outage process is established? iv The key research objectives are: • To consider how process maturity enables improvement. • To identify critical elements in an outage process. • To determine what is included in outage planning, control and improvement. • To identify a suitable process maturity model. • To identify a measurement instrument to determine the maturity level of Eskom’s outage process The research study uses a descriptive research design and applies the survey research method. Greener and Martelli’s (2015: Online) Business Research Process (Sources: Greener & Martelli, 2015: Online) is used together with Farooq’s Research Steps for Survey Research (2015, Online). The survey questionnaire adopted from Smith’s Maintenance Planning and Scheduling Maturity Matrix (2013: Online) was used to develop the survey questionnaire. The author developed the Outage Management Maturity Framework by combining Business Process Management Maturity model and a Maintenance Planning and Scheduling Maturity Matrix. The research finding is that a process maturity model can determine the maturity level of the outage process and is useful as a process improvement tool. The research findings rank the maturity level of the outage process at Level 2, Experimenting.
28
Pantshwa, Athini. "Analysis of the reliability for the 132/66/22 KV distribution network within ESKOM’s Eastern Cape operating unit." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/19750.
Full textAbstract:
A stable and reliable electrical power supply system is an inevitable pre-requisite for the technological and economic growth of any nation. Due to this, utilities must strive and ensure that the customer’s reliability requirements are met and that the regulators requirements are satisfied at the lowest possible cost. It is known fact around the world that 90% of the customer service interruptions are caused due to failure in distribution system. Therefore, it is worth considering reliability assessments as it provides an opportunity to incorporate the cost or losses incurred by the utilities customer as a result of power failure. This must be considered in the planning and operating practices. The system modelling and simulation study is carried out on one of the district’s distribution system which consists of 132 kV, 66 kV and 22 kV network in Aliwal North Sector ECOU. The reliability assessment is done on the 22, 66 and 132 kV system to assess the performance of the present system and also predictive reliability analysis for the future system considering load growth and system expansion. The alternative which gives low SAIDI, SAIFI and minimum breakeven costs is being assessed and considered. The reliability of 132 kV system could be further improved by constructing a new 132 kV line from a different source of supply and connecting with line coming from another district (reserve) at reasonable break even cost. The decision base could be further improved by having Aliwal North Sector context interruption cost. However, the historical data which may be used in Aliwal North Sector to acquire interruption costs from the customers are being proposed. The focus should be on improving the power quality on constrained networks first, then the reliability. Therefore for the Aliwal North power system network it is imperative that Eskom invest on the reliability of this network. This dissertation also analysed load reflected economic benefit versus performance expectations that should be optimized through achieving a balance between network performance (SAIDI) improvement, and total life cycle cost (to Eskom as well as the economy). Reliability analysis conducted in this dissertation used Aliwal North power system network as a case study; the results proved that the system is vulnerable to faults, planned and unplanned outages. Reliability evaluation studies were conducted on the system using DigSilent software in conjunction with FME. These two models gave accurate results with acceptable variance in most indices except for the ENS where the variance was quite significant. It can be concluded that DigSilent results are the most accurate results in all three reliability evaluation scenarios for the Aliwal North Power System, best interpretation being that of DigSilent.
29
Kanduri, Venkata Ramanujam. "Distributed generation impact on fault response of a distrubution [i.e., distribution] network." Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-11122004-151757.
Full text
30
Cunningham, Edward A. IV (Edward Albert). "A portfolio approach to energy governance : state management of China's coal and electric power supply industries." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58272.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Political Science, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 226-244).
This study addresses the extent to which China's central state devolved ownership and investment levels in its energy sector to other actors during the modern reform period (1978- 2008). The project focused on China's coal and electric power industries, leveraging industry and government data, interviews, two firm case studies and a unique survey to measure policy, ownership and investment change over time. The results show that such devolution has been neither incrementally advancing nor consistently lacking, but has fluctuated according to the national electric power balance. The study suggests that China's central state actively manages the range of firms in the strategic coal and electric power industries as a dynamic portfolio of assets, resulting in such fluctuation. These findings run counter to what the dominant theories in the literature would otherwise predict. Neo-liberal theory would predict the incremental reduction of central state ownership in these sectors, as is evident in many of China's other sectors. Arguments predicated on the ability of the central state to sustain "self-reproducing authoritarianism" would predict fairly stable levels of central state investment and ownership in this strategic sector through time as well as quite limited liberalization. Finally, a theory privileging elite politics would indeed predict fluctuations, yet at different turning points in time than those found in this study, and without the sustained pattern that is evident in the extended time period under examination, which spans four distinct political eras.
(cont.) This first implication of this study is that neo-liberal means can be deployed to achieve state-led ends. Second, the study provides evidence that such means of economic liberalization reform need not be cumulative and are, in fact, reversible. Third, the case studies reveal that firm decisions have a significant impact on the execution of these powerful broad central state policy changes that periodically reshape the structure of China's energy sector. Finally, this study also raises important implications relating to public policy, and in particular the ability of the Chinese state to fulfill aggressive greenhouse gas emission reductions in an effort to mitigate climate change.
by Edward A. Cunningham, IV.
Ph.D.
31
Beran, Edward W. "An electromagnetic interference analysis of uninterruptible power supply systems in a data processing environment." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FBeran.pdf.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2002.Thesis advisor(s): Richard W. Adler, Wilbur R. Vincent. Includes bibliographical references (p. 103-104). Also available online.
32
Khobai, Hlalefang. "The relationship between electricity supply and economic growth in South Africa." Thesis, Nelson Mandela Metropolitan University, 2016. http://hdl.handle.net/10948/9251.
Full textAbstract:
Since democratisation of South Africa in 1994, the economy of South Africa underwent significant structural changes. Among these structural changes was electrification for the poor rural areas. During the apartheid era, about two-thirds of the nation lacked access to electricity and hence, provision for electricity to everyone was considered a crucial part of the economic development, post 1994. Since then economic growth and the demand for electricity in South Africa have been increasing at an unprecedented rate. The electricity supply did not increase proportionally to the increase in the consumption of electricity. In responding to the high increase in the demand for electricity, the electricity utility planned to build new power stations and put back in use the ones which were mothballed. But unfortunately the plan for investment in these power stations was late and in 2008, the existing power stations could not manage to supply enough electricity. The demand for electricity was such that it nearly damaged the power generating circuit and the electricity supply utility had to resort to load shedding. The imbalance between electricity supply and demand led to industrial sectors losing on production and as a result led to a downturn in economic growth. It also led to an increase in electricity prices which had a negative effect on individual and private sectors’ purchasing power. It is against this background that this study is designed to investigate the long term relationship between economic growth and electricity supply. The additional variables such as electricity prices, trade openness, capital and employment were included as intermittent variables to form a multivariate framework. This study also assesses the Granger causality between these variables to determine which variable supersedes the other. Two models were applied in this study: The Auto-regressive Distributed Lag (ARDL) bounds approach and the Vector Error Correction Model (VECM) Granger-causality. The ARDL bounds technique was used to detect the long term relationship between economic growth, electricity supply, electricity prices, trade openness, capital and employment using annual data from 1985 to 2014. The ARDL technique was chosen over the conventional models such as Engle and Granger (1987) and Johansen (1988) for the research for the following reasons: Firstly, the ARDL technique uses a single reduced form of equation to examine the long term relationship of the variables as opposed to the conventional Johansen test that employs a system of equations. Secondly, it is suitable to use for testing co-integration when a small sample data is used. Thirdly, it does not require the underlying variables to be integrated of similar order e.g. integrated of order zero I(0), integrated of order one I(1) or fractionally integrated, for it to be applicable. Lastly, it does not rely on the properties of unit root datasets and this makes it possible for the Granger-causality to be applied in testing the long term relationships between the variables. The VECM Granger-causality is used to examine the Granger-causality between the chosen variables. It was chosen for its ability to develop longer term forecasting when dealing with an unconstrained model. The unit root results confirmed that the variables were stationary at first difference using Augmented Dickey Fuller (ADF), Phillips and Perron (PP) and Kwiatkowski-Phillips-Schmidt-Shit (KPSS). The ARDL bound approach outcomes revealed that economic growth, electricity supply, trade openness, electricity prices, employment and capital move together in the long term. There were three co-integrated equations under the export and trade models while under the import model there was one co-integrated equation. The results are such that electricity prices have a negative impact on economic growth. The results further evidenced that; electricity supply, trade openness, employment and capital have a positive impact on economic growth in the long term. The VECM Granger causality findings suggested a unidirectional causality flowing from electricity supply, trade, exports, electricity prices, employment and capital to economic growth in the long term. There was another unidirectional causality established flowing from economic growth, trade openness, electricity prices, employment and capital to electricity supply. A one-way causality flowing from economic growth, electricity supply, electricity prices, employment and capital to export was evidenced. Overall, the study’s results of bidirectional Granger-causality between electricity supply and economic growth have a number of implications for forecasters and policy makers. This feedback hypothesis implies that the high level of economic growth leads to a high level of electricity supply, which would stimulate economic growth. Hence, South Africa demonstrates a kind of electricity dependence in a manner that a sufficiently large supply of electricity seems to ensure high economic growth. Electricity supply is a vitally important factor for economic growth in South Africa. It is therefore necessary that South African policy makers formulate investor friendly policies that will encourage, promote and attract capital inflows to stimulate electricity supply. The South African government needs to primarily deregulate the electricity supply industry which is owned by Eskom (a monopoly), and allow more investors into this industry. The government should promote a change to other forms of energy sources such as renewable energy sources which will play an important role in restoring the balance between electricity supply and consumption. Moreover, it is recommended that the electricity regulator should take steps to curb the severe electricity price increases and to ensure prices affordable to the poor communities. The policy makers need to implement some investor friendly policies that will encourage and promote capital formation. Furthermore, the government should invest towards more job creating sectors such as (Small and Medium Enterprises) SMEs. Finally, the government should take into consideration the importance of trade openness to attract international investments into the economy. It is hoped that the findings of this study would prove beneficial to policy makers in South Africa and elsewhere in the world where power outages are experienced, and assist them in combating the problem.
33
Yang, Gang. "Design of a High Efficiency High Power Density DC/DC Converter for Low Voltage Power Supply in Electric and Hybrid Vehicles." Thesis, Supélec, 2014. http://www.theses.fr/2014SUPL0011/document.
Full textAbstract:
Cette thèse traite de la conception d’un convertisseur DC / DC destiné aux véhicules électriques et hybrides (2,5 kW, 400V/14V, 250kHz). Dérivé de la topologie LLC à résonance, ce convertisseur bénéficie des nombreux avantages propres à cette structure particulière. C’est ainsi que le prototype réalisé présente un rendement très élevé, une densité de puissance très forte avec des perturbations EMI très réduites. La première partie de cette thèse est consacrée à l’analyse théorique du circuit LLC afin de dégager un modèle de conversion et une stratégie de contrôle adaptée à l’application visée. Afin de conserver un rendement important sur une large plage de charge, une structure basée sur la mise en parallèle de deux modules LLC est proposée. Une nouvelle stratégie de contrôle à deux boucles est également proposée pour équilibrer le courant entre les deux modules. La seconde partie de la thèse fait appel à la simulation et à l’expérimentation. Il s’agit de minimiser la masse et l’encombrement tout en maximisant le rendement. Un composant magnétique spécial est conçu puis dimensionné pour intégrer le transformateur et diverses inductances de résonance. Ce convertisseur met également en œuvre un système de redressement synchrone robuste avec une compensation de phase, un module de puissance avec une résistance thermique très faible et un système de refroidissement efficace par air. Le rendement maximal mesuré est 95%. Le rendement demeure supérieur à 94% sur une plage de puissance s’étalant de 500 W à 2 kW. La densité de puissance est 1W/cm3. La CEM du convertisseur est développée dans cette thèseIn this dissertation, a 2.5kW 400V/14V, 250kHz DC/DC converter prototype is developed targeted for electric vehicle/hybrid vehicle applications. Benefiting from numerous advantages brought by LLC resonant topology, this converter is able to perform high efficiency, high power density and low EMI. A first part of this dissertation is the theoretical analysis of LLC: topology analysis, electrical parameter calculation and control strategy. To arrange high output current, this thesis proposes parallel connected LLC structure with developed novel double loop control to realize an equal current distribution. The second part concerns on the system amelioration and efficiency improvement of developed LLC. A special transformer is dimensioned to integrate all magnetic components, and various types of power losses are quantified based on different realization modes and winding geometries to improve its efficiency. This converter also implements a robust synchronous rectification system with phase compensation, a power semiconductor module, and an air-cooling system. The power conversion performance of this prototype is presented and the developed prototype has a peak efficiency of 95% and efficiency is higher than 94% from 500W to 2kW, with a power density of 1W/cm3. The CEM analysis of this converter is also developed in this thesis
34
Cowan, Kelly R. "Technology Planning for Aligning Emerging Business Models and Regulatory Structures: the Case of Electric Vehicle Charging and the Smart Grid." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/4031.
Full textAbstract:
Smart grid has been described as the Energy Internet: Where Energy Technology meets Information Technology. The incorporation of such technology into vast existing utility infrastructures offers many advantages, including possibilities for new smart appliances, energy management systems, better integration of renewable energy, value added services, and new business models, both for supply- and demand-side management. Smart grid also replaces aging utility technologies that are becoming increasingly unreliable, as the average ages for many critical components in utility systems now exceed their original design lives. However, while smart grid offers the promise of revolutionizing utility delivery systems, many questions remain about how such systems can be rolled out at the state, regional, and national levels. Many unique regulatory and market structure challenges exist, which makes it critical to pick the right technology for the right situation and to employ it in the right manner. Technology Roadmapping may be a valuable approach for helping to understand factors that could affect smart grid technology and product development, as well as key business, policy and regulatory drivers. As emerging smart grid technologies are developed and the fledgling industry matures, a critical issue will be understanding how the combination of industry drivers impact one another, what barriers exist to achieving the benefits of smart grid technologies, and how to prioritize R&D and acquisition efforts. Since the planning of power grids often relies on regional factors, it will also be important investigate linkages between smart grid deployment and regional planning goals. This can be used to develop strategies for overcoming barriers and achieving the benefits of this promising new technology. This research builds upon existing roadmapping processes by considering an integrated set of factors, including policy issues, which are specifically tuned to the needs of smart grids and have not generally been considered in other types of roadmapping efforts. It will also incorporate expert judgment quantification to prioritize factors, show the pathways for overcoming barriers and achieving benefits, and discussing the most promising strategies for achieving these goals.
35
Myhre, Jørgen Chr. "Electrical Power Supply to Offshore Oil Installations by High Voltage Direct Current Transmission." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-383.
Full textAbstract:
This study was initiated to investigate if it could be feasible to supply offshore oil installations in the North Sea with electrical power from land. A prestudy of alternative converter topologies indicated that the most promising solution would be to investigate a conventional system with reduced synchronous compensator rating.
The study starts with a summary of the state of power supply to offshore installations today, and a short review of classical HVDC transmission. It goes on to analyse how a passive network without sources influences the inverter. The transmission, with its current controlled rectifier and large inductance, is simulated as a current source. Under these circumstances the analysis shows that the network frequency has to adapt in order to keep the active and reactive power balance until the controllers are able to react. The concept of firing angle for a thyristor is limited in a system with variable frequency, the actual control parameter is the firing delay time.
Sensitivity analysis showed some astonishing consequences. The frequency rises both by an increase in the active and in the reactive load. The voltage falls by an increase in the active load, but rises by an increase in the inductive load.
Two different control principles for the system of inverter, synchronous compensator and load are defined. The first takes the reference for the firing delay time from the fundamental voltage at the point of common coupling. The second takes the reference for the firing delay time from the simulated EMF of the synchronous compensator. Of these, the second is the more stable and should be chosen as the basis for a possible control system.
Two simulation tools are applied. The first is a quasi-phasor model running on Matlab with Simulink. The other is a time domain model in KREAN. The time domain model is primarily used for the verification of the quasi-phasor model, and shows that quasi-phasors is still a valuable tool for making a quick analysis of the main features when the details of the transients are of less importance.
The study indicates that power supply by HVDC transmission from land to offshore oil installations could be technically feasible, even without the large synchronous compensators normally required. It has been shown that in a network only supplied by an inverter, variations of active and reactive loads have significant influence on both voltage and frequency. Particularly it should be noted that the frequency shows a positive sensitivity to increases in load. This could make the system intrinsically unstable in the case of a frequency dependent load such as motors.
It was not a part of the study to optimize controllers, but even with simple controllers it was possible to keep the frequency within limits given by norms and regulations, but the voltages were dynamically outside the limits, though not very far. These voltage overswings take place in the first few instances after a disturbance, so it takes unrealistically fast controllers to handle them. They are partly due to the model, where the land based rectifier and the DC reactors are simulated by a constant current source, but partly they have to be handled by overdimensioning of the system.
The simulations indicate that it should be technically possible to supply an oil platform with electrical power from land by means of HVDC transmission with small synchronous compensators. Whether this is financially feasible has not been investigated. Neither has it been considered whether the necessary equipment can actually be installed on an oil platform.
Recently both ABB and Siemens have presented solutions for HVDC transmission in the lower and medium power range based on voltage source converters based on IGBTs. Fully controllable voltage source HVDC converters have properties that may be better suited than conventional line commutated current source thyristor inverters, to supply weak or passive networks, such as offshore oil installations, with electrical power. But they also have some disadvantages, and a complete technical and financial comparison must be performed in order to decide about any potential project.
36
Kamran, Farrukh. "A new UPS topology and deadbeat control techniques for improved utility interface compatibility." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/15773.
Full text
37
Alghamdi, Turki. "Interactions of Connected Electric Vehicles with Modern Power Grids in Smart Cities." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42513.
Full textAbstract:
In a smart city, it is vital to provide a clean and green environment by curbing air pollution and greenhouse gas emissions (GHGs) from transportation. As a recent action from many governments aiming to minimize transportation’s pollution upon the climate, new plans have been announced to ban cars with gas engines throughout the world. Therefore, it is anticipated that the presence of electric vehicles (EVs) will grow very fast globally. Consequently, the necessity to establish electric vehicle supply equipment (EVSE) in the smart city through public charging stations is growing incrementally year by year. However, the EV charging process via EVSE which is primarily connected to the power grid will put high pressure upon the centralized power grid, especially during peak demand periods. Increasing the power production of power grid will increase the environmental impact. Therefore, it is fundamental for the smart city to be equipped with a modern power grid to cope with the traditional power grid’s drawbacks.
In this thesis, we conduct an in-depth analysis of the problem of EVs’ interaction with the modern power grid in a smart city to manage and control EV charging and discharging processes. We also present various approaches and mechanisms toward identifying and investigating these challenges and requirements to manage the power demand. We propose novel solutions, namely Decentralized-EVSE (D-EVSE), for EVs’ charging and discharging processes based on Renewable Energy Sources (RESs) and an energy storage system. We present two algorithms to manage the interaction between EVs and D-EVSE while maximizing EV drivers’ satisfaction in terms of reducing the waiting time for charging or discharging services and minimizing the stress placed on D-EVSE. We propose an optimization model based on Game Theory (GT) to manage the interaction between EVs and D-EVSE. We name this the decentralized-GT (D-GT) model. This model aims to find the optimal solution for EVs and D-EVSE based on the concept of win-win. We design a decentralized profit maximization algorithm to help D-EVSE take profit from the electricity price variation during the day when selling or buying electricity respectively to EVs or from the grid or EVs as discharging processes. We implement different scenarios to these models and show through analytical and simulation results that our proposed models help to minimize the D-EVSE stress level, increase the D-EVSE sustainability, maximize the D-EVSE profit, as well as maximize EV drivers’ satisfaction and reduce EVs’ waiting time.
38
Rossouw, Claire Angela. "The accelerated life cycle testing and modelling of Li-ion cells used in electric vehicle applications." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1012709.
Full textAbstract:
Li-ion batteries have become one of the chosen energy storage devices that are used in applications such as power tools, cellular phones and electric vehicles (EV). With the demand for portable high energy density devices, the rechargeable Li-ion battery has become one of the more viable energy storage systems for large scale commercial EVs because of their higher energy density to weight or volume ratio when compared to other current commercial battery energy storage systems. Various safety procedures for the use of Li-ion batteries in both consumer and EV applications have been developed by the international associations. The test procedures studied in this dissertation demonstrated the importance of determining the true capacity of a cell at various discharge rates. For this, the well known Peukert test was demonstrated. The study also showed that cells with different battery geometries and chemistries would demonstrate different thermal heating during discharge and slightly different Ragone results if different test methods were used as reported in the literature. Accelerated ageing tests were done on different cells at different Depth-of-Discharge (DoD) regions. The different DoD regions were determined according to expected stresses the electrode material in a cell would experience when discharged to specific DoD that follows the discharge voltage profile. Electrochemical Impedance Spectroscopy (EIS) was used to measure various electrochemical changes within these cells. The EIS results showed that certain observed modelled parameters would change similarly to the ageing of the cell as it aged due to the accelerated testing. EIS was also done on cells at different State-of-Charge (SoC) and temperatures. The results showed that EIS can be used as an effective technique to observe changes within a Li-ion cell as the SoC or temperature changed. For automotive vehicles that are powered by a fuel cell or battery, a supercapacitor can be coupled to a battery in order to increase and optimize the energy and power densities of the drive systems. A test procedure in the literature that evaluated the use of capacitors with Pb-acid batteries was applied to Li-ion type cells in order to quantify the increased power due to the use of a supercapacitor with a Li-ion cell. Both a cylindrical LiCoO2 cell and a VRLA Pb-acid cell showed some additional charge acceptance and delivery when connected to the supercapacitors. A LiMn2O4 pouch cell showed significant charge acceptance and delivery when connected to supercapacitors. The amount of additional charge acceptance and delivery of the different combinations could be explained by EIS, in particular, the resistance and capacitance of the cell in comparison to the combination of the cell and supercapacitor. A large capacity LiCoO2 cell showed high charge acceptance and delivery without connection with a supercapacitor. The study proved that EIS can be used to model the changes within cells under the different conditions and using different test procedures.
39
Zhou, Chen. "Design and analysis of an active power factor correction circuit." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/53729.
Full textAbstract:
The design of an active-unity power factor correction circuit with variable-hysteresis
control for off-line dc-to-dc switching power supplies is described. Design
equations relating the boost inductor current ripple to the circuit components selection
and circuit performance arc discussed. A computer-aided design program (CADO) is
developed to give the optimal circuit components selection. A 500 watt, 300 volt experimental
circuit is built to verify the simulation and analysis results.
The control-to-output response of the power factor circuit is verified with the experimental
results. Design guidelines for the low-frequency feedback network are presented.
Small-signal closed-loop responses are measured with an experimental power
factor circuit.Master of Science
40
Gray, Matthew Alan. "A comparative analysis of proportional-integral compensated shunt active power filters." Master's thesis, Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-11092004-083404.
Full text
41
Barnes, Lemuel Gregory. "Voltage-source inverter output waveform compensation using adaptive intelligent control /." This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-10192006-115605/.
Full text
42
Seimbille, Denis. "Design of power supply system in DC electrified transit railways - Influence of the high voltage network." Thesis, KTH, Elektrisk energiomvandling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153924.
Full textAbstract:
Urban rail systems such as subways and trams transport millions of people every day, oering a high level of service. Most of these systems are fed by direct current (DC). The design of the power supply network of DC electried transit railways is of great importance and requires the use of simulation models. The power supply network is composed of a high voltage network (fed with AC) linked to a traction network (fed with DC) by traction substations. Many simulation models ignore the high voltage network in the design process whereas it has a signicant inuence on the results. A Newton-Raphson algorithm is implemented to solve the AC load ow in the high voltage network, and coupled to the existing simulation software Symphonie. Three dierent high voltage network architectures are simulated, and the simulation results are analyzed. The results show that the voltage drop at the AC side of traction substations and the load sharing between them varies signicantly from one architecture to another. In particular, when several traction substations are connected to the same high voltage loop, voltage drops can be signicant for some traction substations. In conclusion, the design of the power supply network of DC electried transit railways requires the simulation of the high voltage network when several substations are connected to the same high voltage loop.Publika sparburna transportsystem sasom tunnelbanor och lokalbanor transporterar miljontals manniskor varje dag. De esta korta linjer matas med likstrom. Utformningen av stromforsorjningen till dessa system ar avgorande for ett val fungerande , och forutsatter anvandningen av olika matematiska modeller. Detta natverk bestar av ett vaxelstroms hogspanningsnat som omformas till likstrom i era banmatningsstationer langs banan. Dessa matematiska modeller ignorerar dock ofta hogspanningsdelen i modelleringen, varfor resultatet ibland kan bli missvisande. I detta arbete har en belastningsfordelningsalgoritm baserad pa Newton-Raphsons metod implementerats for att skapa en battre modellering av hsgspanningsdelen i den bentliga programvaran Symphonie. Tre olika hogspanningsstrukturer har bearbetats och resultatet visar att spanningsfall och belastningsf ordelning varierar mellan de olika strukturerna. Speciellt nar era transformatorstationer ar kopplade till samma hogspanningssystem, kan spanningsfall vara patagligt for vissa transformatorstationer. Sammanfattningsvis maste utformningen av hogspanningsystemet till likstromsforsorjda jarnvagar utformas med hjalp av anpassade matematiska modeller som tar hansyn till placering av transformatorstationer liksom hogspanningsnatets kapacitet.
43
Grobler, Frederik Antonie. "The development of harmonic content and quality of electricity supply measuring system incorporating scada processing." Thesis, Bloemfontein : Central University of Technology, Free State, 2005. http://hdl.handle.net/11462/61.
Full textAbstract:
Thesis (D.Tech (Engineering Electrical)) - Central University of Technology, Free State, 2005When Thomas Edison invented his carbon filament lamp in 1879, gas shares fell overnight. A committee of inquiry was set up to examine the future possibilities of the new method of lighting, and had reached the conclusion that electric light in the home was fanciful and absurd. Today electric light burns in practically every house in the civilised world, with many great advances in the production and use of electricity and electric power supplied by various utilities. The objective of the electric utility to deliver pure sinusoidal voltage at fairly constant magnitude throughout their system is complicated by the fact that there are currently loads on the system that produce harmonic voltages, which result in distorted voltages and currents that can adversely impact on the system performance in different ways. Because the numbers of harmonic producing loads have increased over the years, it has become necessary to address their influence, when making any additions or changes to an installation. Quality of supply measurements have long been used to characterise non-linearity on the power system, and have traditionally been measured with expensive portable analysers. A potentially faster, more integrated, and more flexible solution to measure the harmonics with a Supervisory System is accomplished by this research. Any script which aspired to cover in full detail the whole field of a subject so enormous as techniques to measure the quality of electricity supply on a SCADA system, would hardly be practical in less than a few volumes. The pretensions of this research are both modest and of a more immediate value to the reader.
44
Marais, Charel. "Analysis of fuel consumption reduction potential through the use of an electrically driven air conditioning compressor." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/774.
Full textAbstract:
The disturbing current situation regarding the world climate has initiated a major wave of urgent developments towards decreasing the overall impact of human activities on the living environment. A major role player in this development is the automobile industry that is inherently connected to pollution of various types, be it air, water or noise pollution. There have been drastic changes not only in the technologies employed in producing vehicles and components, but also in the construction and technologies built into modern automobiles to lessen the overall environmental impact of the industry. Noxious emissions have been decreased, overall efficiencies increased and vehicles are becoming more economical with each new generation. Stricter laws dictate that the level of acceptable vehicle emissions is to be decreased ever further and all manufacturers are developing various possibilities to achieve this. With the emergence of hybrid vehicle technology, there was also a sudden development of different electrical systems that were made viable by the higher onboard voltage systems employed in hybrid vehicles. One of these developments was the electrical air conditioning compressor for use in automobile applications. Although it is designed to operate with a higher voltage than the traditional 12V onboard vehicle systems, it is theoretically possible to incorporate it into a 12V system by making use of a DC-DC converter to step up the supply voltage of the electrical compressor sufficiently to allow for its successful operation. The question therefore arises whether it would be feasible and sensible to employ an electrical air conditioning system in conventional combustion engine vehicles from an overall fuel consumption and vehicle emissions point of view. A modelling approach was taken where an overall vehicle driving simulation was created to represent an average modern production vehicle. The simulation was then extended to include the options of incorporating models for both mechanically and electrically driven air conditioning systems. This provides insight into the influences of the air conditioning system on the vehicle’s overall fuel consumption and an opportunity to compare the influences from the two different systems. This study attempted to provide answers to some of the viability questions regarding the incorporation of electrically driven air conditioning systems into vehicles that use standard 12V onboard voltage systems. It was found that the electrical system has definite potential as a viable replacement option for the conventional system should it be combined with an appropriate alternator and equipped with an efficient control system.
45
Collins, Edward Randolph Jr. "Torque and speed control of single-phase induction motors using an adjustable amplitude and phase angle auxiliary winding power supply." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/15472.
Full text
46
Malgas, Isaac. "Towards risk management in a deregulated and competitive electricity supply industry." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53195.
Full textAbstract:
Thesis (MBA)--Stellenbosch University, 2002.ENGLISH ABSTRACT: The energy sector of the South African economy is poised to change in extraordinary ways. In just a few short years from now, the days will be gone when generators are guaranteed of their income and where regional distributors have the monopoly in the regions that they are servicing. Other energy markets in the world, such as oil and gas, have been free of regulation for many years. More recently, local policymakers have been focussing on increasing competition in the electricity sector and in so doing, liberate electric utilities from government's long established control. The shift away from government regulation of energy will lead to something even more important than placing downward pressure on the price of a MWh. It will instigate the development of multiple trading centres and platforms that are dedicated to competition in the free trade of electricity and related products. With the deregulation of the electricity supply industry and the inevitable introduction of competition, the real risks of energy trading will be faced by generators and distributors alike. This research investigates the changes that are set to occur within the next few years, based on developments that have unfolded in countries where electricity supply industries have been privatised and utilities and distributors are managing their risks in this new competitive environment. It explains how the South African Electricity Supply Industry may change with respect to the develop of markets which provide risk cover to industry players, the practices assumed by utilities in international electricity supply industries to minimise their risk exposure, and how industry players can use derivative instruments to manage their risks better.
AFRIKAANSE OPSOMMING: Die elektrisiteitsvoorsieningssektor is gereed om groot veranderings te maak. Binne 'n paar jaar, sal ons die einde sien van die dae waar kragstasies gewaarborg is van hulle inkomste en waar streeksvoorsieners die monopolie het in die streke waarin hulle verskaf. Ander energie markte in die wêreld, soos die van olie en natuurlike gas, is al sonder regulering vir baie jare. Meer onlangs het beleidsrade hul tyd toegewy aan die instelling van kompetisie in die elektrisiteitsvoorsieningssektor om utiliteitsmaatskappye vry te maak van staatsbeheer. Hierdie beweging weg van staatsbeheer sal lei na iets meer as net die afwaardse druk op die prys van 'n MWh. Dit sal die begin merk van die ontwikkeling van veelvoudige verhoë wat toegewyd is aan kompetisie in die vrye handel van elektrisiteit en soortgelyke produkte. Met die deregulering en die onvermydelike indiening van kompetisie, sal die ware risikos van energie handel aanvaar word deur voortbrengers en verskaffers van elektrisiteit. Hierdie navorsing stel ondersoek in die veranderings wat van plan is om te gebeur in die volgende paar jaar en is gebaseer op die ontwikkelinge wat in lande afgespeel het waar elektrisiteitsvoorsieningsnywerhede geprivatiseer is en waar voortbrengers en verskaffers van elektrisiteit hulle risikos bestuur in hierdie nuwe mededingende sektor. Dit verduidelik hoe die Suid-Afrikaanse elektrisiteitsvoorsieningsnywerheid mag verander teen opsigte van die ontwikkeling van markte wat risiko versekering aanbied vir utiliteitsmaatskappye, die praktyke wat deur hierdie spelers toegepas word om hulle blootstelling aan risikos te verminder, en ook hoe hulle afgeleide instrumente gebruik om hulle risikos beter te bestuur.
47
Cetinkaya, Suleyman. "Repetitive Control Of A Three-phase Uninterruptible Power Supply With Isolation Transformer." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608150/index.pdf.
Full textAbstract:
A repetitive control method for output voltage control of a three phase uninterruptible power supply (UPS) with isolation transformer is investigated. In the method voltage control loop is employed in the stationary dq frame. The controller eliminates the periodic errors on the output voltages due to inverter voltage nonlinearity and load disturbances. The controller design and implementation details are given. The controller is implemented on a 5-kVA UPS prototype which is
constructed in laboratory. Linear and nonlinear loads for balanced and unbalanced load operating conditions are considered. The steady-state and dynamic performance of the control method are investigated in detail. The theory of the control strategy is verified by means of simulations and experiments.
48
Ishaque, Mohammed. "A new method for calculating the economic benefits of varying degrees of power factor correction for industrial plant loads." PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/4322.
Full textAbstract:
A comparative study of the economic benefits that can be obtained from different degrees of power factor correction for medium and small scale industrial installations is shown. A new approach for precise calculation of kws and kvars required at different power factors is presented. These calculated values are used to find the return on investments for the capacitors needed for power factor correction. The developed method is easy to use, cost effective, accurate and will help electrical engineers with minimum knowledge of power systems to precisely determine the savings available by improving the power factor of an industrial load.
49
ZANINI, ALEXANDRE. "ECONOMIC REGULATION IN THE BRAZILIAN ELECTRIC POWER SUPPLY SECTOR: A METHODOLOGY FOR DEFINING PRODUCTION EFFICIENCY FRONTIER AND ESTIMATING THE X-FACTOR." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5566@1.
Full textAbstract:
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOO setor elétrico nos últimos anos vem passando por grandes mudanças estruturais em diversas regiões do planeta. Essas mudanças são devidas a processos de reestruturação do setor energético visando o aumento da eficiência e da qualidade. No Brasil, para este fim, foram criados órgãos responsáveis pelo setor, de modo que se viabilizem e regulamentem estas mudanças, seja por meio da criação de instrumentos de incentivos à competição ou permitindo a participação de agentes privados nos processos de geração, distribuição e comercialização de energia. Neste contexto foi criada a ANEEL (Agência Nacional de Energia Elétrica), responsável por instituir as regras de mercado de energia elétrica visando assegurar a competitividade do setor. Dentro das atribuições da ANEEL, está a realização de revisões tarifárias periódicas. Esta revisão tarifária compreende: a) reposicionamento das tarifas de fornecimento de energia elétrica em nível compatível com a preservação do equilíbrio econômico-financeiro do contrato de concessão; e b) determinação do Fator X que será aplicado nos reajustes tarifários com o objetivo de compartilhar ganhos de produtividade com os consumidores. Para determinar o Fator X é necessário medir a eficiência, o que pode ser feito basicamente através de duas alternativas: 1) comparar a empresa com fronteiras de eficiência construídas para o mercado regulado a partir de grupos de similaridade; 2) comparar a empresa com o mercado não regulado. Desta forma, o objetivo da tese é propor uma metodologia para definição de fronteiras de eficiência entre as empresas de distribuição de energia elétrica através da conjugação de redes neurais e de modelos econométricos, particularmante, os modelos de análise de fronteira estocástica.
In recent years, the electric power supply sector has undergone major structural changes in a variety of regions throughout the planet. These changes are due to restructuring processes taking place in the energy sector towards the increase of quality and efficiency. In Brazil, it was created agencies responsible for the sector, in order to foster and regulate those changes, either by means of creating instruments for promoting competition or by allowing private agents participation in the processes of generating, distributing and trading energy. In this context, it was created the Brazilian Electricity Regulatory Agency (ANEEL), responsible for binding rules to assure market competition in the electric power supply sector. Among the duties of the regulatory agency of the electric power supply sector in Brazil there is the periodical revision of energy prices. Such revisions involve estimating the X Factor applied to update prices so that gains in productivity are shared with consumers. To estimate the X Factor it is necessary to measure efficiency and, for this, two issues are important: the choices of benchmarks and of techniques for productivity measurement. This thesis proposes an approach to define frontier efficiency of electric power distribution utilities based on clustering homogeneous utilities using neural networks and estimating the frontiers through econometric techniques.
50
Groves, James O. "Small signal analysis of nonlinear systems with periodic operating trajectories." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06062008-162614/.
Full text