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Full-Text Articles in Science and Technology Studies

Power Sharing Among Multiple Solar Photovoltaic (Pv) Systems In A Radial Distribution Feeder, Brian K. Perera, Philip Ciufo Apr 2015

Power Sharing Among Multiple Solar Photovoltaic (Pv) Systems In A Radial Distribution Feeder, Brian K. Perera, Philip Ciufo

Dr Philip Ciufo

With an increasing penetration of solar photovoltaic (PV) systems, power distribution grids are becoming more susceptible to network voltage rise. As per applicable standards for grid-integrated PV systems, a PV system must be automatically disconnected from the grid when the terminal voltage of the PV system exceeds a defined maximum voltage. With this directive, in certain situations, PV systems connected at nodes at which the voltage sensitivity is high, may be disconnected from the grid while PV systems connected at less sensitive nodes are continuing to operate. In such a situation, owners whose PV systems are connected at nodes at ...


Novel Modulation And Control Strategy For Five-Level Anpc Converter With Unbalanced Dc Voltage Applied To A Single-Phase Grid Connected Pv System, Hamid R. Teymour, Danny Sutanto, Kashem M. Muttaqi, Phil Ciufo Apr 2015

Novel Modulation And Control Strategy For Five-Level Anpc Converter With Unbalanced Dc Voltage Applied To A Single-Phase Grid Connected Pv System, Hamid R. Teymour, Danny Sutanto, Kashem M. Muttaqi, Phil Ciufo

Dr Philip Ciufo

This paper proposes a new control strategy and a novel modulation technique for a grid-connected photo-voltaic (PV) system using a single-phase five-level flying capacitor (FC) based active-neutral-point-clamped (ANPC) converter. The proposed modulator can control the FC voltage to follow the requested reference value and simultaneously generate the required ac output voltage regardless of the values of the dc capacitor voltages of the converter. By implementing this method, smaller values of dc-link and flying capacitors can be used even in applications that could experience ripple or transient in the capacitors voltage. In the grid-connected single-phase five-level ANPC, where the capacitors can ...


Statistical Analysis Of Overvoltages Due To The Energisation Of A 132 Kv Underground Cable, M Z. Daud, P Ciufo, S Perera Apr 2015

Statistical Analysis Of Overvoltages Due To The Energisation Of A 132 Kv Underground Cable, M Z. Daud, P Ciufo, S Perera

Dr Philip Ciufo

Analysis by means of simulation studies is essential for providing useful information to distribution engineers and researchers regarding high frequency switching transients in cable systems. The behaviour of transients due to switching is strongly dependent on the pole closing span of the circuit breaker and also the closing angle of the power frequency voltage. This behaviour requires the study of overvoltage magnitude distributions to be carried out using a statistical approach. This paper presents an analysis of overvoltage sensitivity due to circuit breaker operations when energising an unloaded 132 kV underground cable system. Based on two approaches, the overvoltage values ...


A Review Of Recent Investigations On Voltage Unbalance Management: Further Contributions To Improvement Of Iec/Tr 61000-3-13:2008, Jayatunga Vitharanage Upuli Priyadarshani Jayatunga, Sarath Perera, Philip Ciufo, Ashish Agalgaonkar Apr 2015

A Review Of Recent Investigations On Voltage Unbalance Management: Further Contributions To Improvement Of Iec/Tr 61000-3-13:2008, Jayatunga Vitharanage Upuli Priyadarshani Jayatunga, Sarath Perera, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

Voltage unbalance (VU) management in power systems essentially involves two major aspects: VU emission allocation at the pre-connection stage and compliance assessment at the post-connection stage of installations. This is a summary and a review paper on the recent investigations completed in relation to VU emission assessment techniques which provide further contributions to the improvement of IEC Technical Report IEC/TR61000-3-13:2008. Generalised approaches developed for the classification of different sources of unbalance at the point of evaluation (covering both radial and interconnected networks) and the evaluation of their individual contributions giving emphasis to the discrimination between customer and network ...


Solar Pv And Battery Storage Integration Using A New Configuration Of A Three-Level Npc Inverter With Advanced Control Strategy, Hamid Teymour Ghasemabadi, Danny Soetanto, Kashem M. Muttaqi, Philip Ciufo Apr 2015

Solar Pv And Battery Storage Integration Using A New Configuration Of A Three-Level Npc Inverter With Advanced Control Strategy, Hamid Teymour Ghasemabadi, Danny Soetanto, Kashem M. Muttaqi, Philip Ciufo

Dr Philip Ciufo

In this paper, a novel configuration of a three-level neutral-point-clamped (NPC) inverter that can integrate solar photovoltaic (PV) with battery storage in a grid-connected system is proposed. The strength of the proposed topology lies in a novel, extended unbalance three-level vector modulation technique that can generate the correct ac voltage under unbalanced dc voltage conditions. This paper presents the design philosophy of the proposed configuration and the theoretical framework of the proposed modulation technique. A new control algorithm for the proposed system is also presented in order to control the power delivery between the solar PV, battery, and grid, which ...


Power Quality Emission Assessment Of Photovoltaic Inverters Based On Iec Technical Report 61000-3-15:2011, Devinda Perera, Philip Ciufo, Lasantha G. Meegahapola, Sarath Perera Apr 2015

Power Quality Emission Assessment Of Photovoltaic Inverters Based On Iec Technical Report 61000-3-15:2011, Devinda Perera, Philip Ciufo, Lasantha G. Meegahapola, Sarath Perera

Dr Philip Ciufo

The International Electrotechnical Committee Technical Report IEC 61000-3-15:2011 provides electromagnetic compatibility requirements and test conditions for distributed generators up to 75 A per phase. In the current research, two commercially available photovoltaic (PV) inverters up to the capacity of 3600 W were tested following the guidelines proposed in IEC 61000-3-15 in relation to low order harmonic emission and flicker emission. In addition, the harmonic and flicker emission behaviour of the PV inverters were investigated under varying irradiation conditions. Both PV inverters were observed to comply with the emission requirements prescribed by the technical report under most conditions except for ...


Fault Approximation Tool For Grid-Connected Inverter-Interfaced Distributed Generators, Joel Kennedy, Philip Ciufo, Ashish Agalgaonkar Apr 2015

Fault Approximation Tool For Grid-Connected Inverter-Interfaced Distributed Generators, Joel Kennedy, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

A novel fault approximation tool (FAT) is presented for use in distribution networks with a high penetration of inverter-interfaced distributed generation. The FAT does not rely on balanced operation nor an absolute reference point for voltage calculations, both of which are required for Newton-Raphson load flow calculations. Simulations show that the FAT provides an accurate representation of the transient and steady-state fault response for unbalanced faults when juxtaposed with a detailed small-signal model. The `sub-transient' response of the inverter-interfaced distributed generation is omitted to remove data considered extraneous from the perspective of distribution line protection analysis. The FAT is not ...


Performance Of Adjustable Speed Drives Subject To Regular Voltage Fluctuations, Kun Zhao, Philip Ciufo, Sarath Perera Apr 2015

Performance Of Adjustable Speed Drives Subject To Regular Voltage Fluctuations, Kun Zhao, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

The impact of power quality disturbances on customer equipment has been a topic of interest to equipment manufacturers, electricity utilities, customers and to those involved in the development of electromagnetic compatibility standards. Recently, a new interest has developed in the possible impact of voltage fluctuations on customer equipment because of suggestions to relax voltage fluctuation limits and hence the flicker limits in power systems. With a view to contribute to this understanding, this paper investigates the performance of an adjustable speed drive (ASD) when subjected to sinusoidal regular voltage fluctuations. When the ASD is operating in open loop mode, the ...


A Sensitivity Analysis Toolkit For The Simplification Of Mv Distribution Network Voltage Management, Fabian Tamp, Philip Ciufo Apr 2015

A Sensitivity Analysis Toolkit For The Simplification Of Mv Distribution Network Voltage Management, Fabian Tamp, Philip Ciufo

Dr Philip Ciufo

As distribution networks become increasingly variable and generation becomes increasingly decentralised, voltage standards are becoming more liable to violation. Accordingly, intelligent voltage management strategies are required to enable standards compliance without unduly increasing network maintenance or infrastructure costs. The relationship between network power and voltages, however, is complex, non-linear and interdependent, and thus is difficult to conceptualise and use for decision-making and control purposes. This paper introduces a software toolkit that simplifies the development of voltage management strategies by the application of sensitivity analysis. Sensitivity analysis reduces complex network relationships to simple linear equations, and thus enables easy and comprehensive ...


Microgrids Of Commercial Buildings: Strategies To Manage Mode Transfer From Grid Connected To Islanded Mode, Lasantha Meegahapola, Duane A. Robinson, Ashish Agalgaonkar, Sarath Perera, Philip Ciufo Apr 2015

Microgrids Of Commercial Buildings: Strategies To Manage Mode Transfer From Grid Connected To Islanded Mode, Lasantha Meegahapola, Duane A. Robinson, Ashish Agalgaonkar, Sarath Perera, Philip Ciufo

Dr Philip Ciufo

Microgrid systems located within commercial premises are becoming increasingly popular and their dynamic behavior is still uncharted territory in modern power networks. Improved understanding in design and operation is required for the electricity utility and building services design sectors. This paper evaluates the design requirements for a commercial building microgrid system to facilitate seamless mode transition considering an actual commercial building microgrid system. A dynamic simulation model of the proposed microgrid system is established (utilizing DIgSILENT Power Factory) to aid the development of planning and operational philosophy for the practical system. An economic operational criterion is developed for the microgrid ...


Balancing Energy In The Smart Grid Using Distributed Value Function (Dvf), Hassan Shirzeh, Fazel Naghdy, Philip Ciufo, Montserrat Ros Apr 2015

Balancing Energy In The Smart Grid Using Distributed Value Function (Dvf), Hassan Shirzeh, Fazel Naghdy, Philip Ciufo, Montserrat Ros

Dr Philip Ciufo

As the penetration of renewable energy resources increases in distribution networks, so does the need to manage these resources in an effective manner. Since these resources are installed to displace carbon-based generation and to provide an income stream to the resource owner, it is important that both installation objectives (as a minimum) can be met. With all of these renewable energy resources available, the opportunity also exists to assist with the energy management of this resource-rich distribution network. However, the renewable energy resources do not produce power in a deterministic manner. The available production depends on the time of day ...


Voltage Unbalance Emission Assessment In Interconnected Power Systems, Jayatunga Vitharanage Upuli Priyadarshani Jayatunga, Sarath Perera, Philip Ciufo, Ashish Agalgaonkar Apr 2015

Voltage Unbalance Emission Assessment In Interconnected Power Systems, Jayatunga Vitharanage Upuli Priyadarshani Jayatunga, Sarath Perera, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

The International Electrotechnical Commission (IEC) Technical Report IEC/TR 61000-3-13:2008 considers voltage unbalance (VU) emission assessment as a key aspect of the VU management of power systems. Compliance assessment of unbalanced installations at the post connection stage is essential to ensure that the limits set by the IEC VU emission allocation methodology in the pre-connection stage are met. Although VU is known to be caused by load asymmetries and inherent network asymmetries, locating all VU emission sources is not a straightforward process, especially in a network with interconnections. Such assessment methodologies should ensure that the contributions from various sources ...


Voltage Unbalance Emission Assessment: Sources Of Contribution And Their Ranking, U Jayatunga, Sarath Perera, P Ciufo, A P. Agalgaonkar Apr 2015

Voltage Unbalance Emission Assessment: Sources Of Contribution And Their Ranking, U Jayatunga, Sarath Perera, P Ciufo, A P. Agalgaonkar

Dr Philip Ciufo

etermining sources of voltage unbalance (VU) and quantifying their individual contributions in an interconnected network is a complex task due to multiple interactions that take place between them. Post-connection VU emission assessment techniques in relation to customer installations are important not only in compliance assessment according to IEC/TR 61000-3- 13:2008 Limits - Assessment of emission limits for the connection of unbalanced installations to MV, HV and EHV power systems, but also in determining the various emission contributors in the power system being considered. This paper presents a case study on the application of a recently developed post-connection VU emission ...


Point Of Common Coupling (Pcc) Voltage Control Of A Grid-Connected Solar Photovoltaic (Pv) System, Brian K. Perera, Philip Ciufo, Sarath Perera Apr 2015

Point Of Common Coupling (Pcc) Voltage Control Of A Grid-Connected Solar Photovoltaic (Pv) System, Brian K. Perera, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

In future low voltage grids, with multiple inverter interfaced sources connected, voltage regulation may become a necessary task. The potential exists for inverter interfaced sources to be deployed to regulate the voltage at the point of common coupling (PCC) of each inverter interfaced sources. The PCC voltage regulation is attainable with inverter interfaced sources by dynamically controlling the amount of reactive power injected to the power distribution grid by individual systems. In the current research, a closed-loop controller is proposed to regulate the PCC voltage of a solar photovoltaic (PV) system that is connected to a single-phase power distribution feeder ...


Over-Voltage Mitigation Within Distribution Networks With A High Renewable Distributed Generation Penetration, Joel Kennedy, Philip Ciufo, Ashish Agalgaonkar Apr 2015

Over-Voltage Mitigation Within Distribution Networks With A High Renewable Distributed Generation Penetration, Joel Kennedy, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

The rapid growth of grid-connected distributed generation has increased the likelihood of over-voltage occurrences in distribution networks. In recent times, much research has taken place in order to develop a control strategy to mitigate the voltage rise problem. However, most of the published strategies require re-tuning when additional resources are connected, or have a strong dependence on network parameters, such as fault level. This paper proposes a novel over-voltage mitigation scheme that has many advantages not observed in literature. Firstly, the control scheme can integrate with an existing feeder in a plug-and-play fashion. No prior analysis is necessary to configure ...


Adaptive Stochastic Energy Flow Balancing In Smart Grid, Hassan Shirzeh, Fazel Naghdy, Philip Ciufo, Montserrat Ros Jan 2014

Adaptive Stochastic Energy Flow Balancing In Smart Grid, Hassan Shirzeh, Fazel Naghdy, Philip Ciufo, Montserrat Ros

Dr Philip Ciufo

A smart grid can be considered as an unstructured network of distributed interacting nodes represented by renewable energy sources, storage and loads. The nodes emerge or disappear in a stochastic manner due to the intermittent nature of natural sources such as wind speed and solar irradiation. Prediction and stochastic modelling of electrical energy flow is a critical characteristic in such a network to achieve load balancing and/or peak shaving in order to minimise the fluctuation between off peak and peak demand by power consumers. Before contributing energy to the network, a node acquires information about other nodes in the ...


Rectifier Capacitor Filter Stress Analysis When Subject To Regular Voltage Fluctuations, Kun Zhao, Phil Ciufo, Sarath Perera Jan 2014

Rectifier Capacitor Filter Stress Analysis When Subject To Regular Voltage Fluctuations, Kun Zhao, Phil Ciufo, Sarath Perera

Dr Philip Ciufo

Lamp flicker levels which arise as a result of voltage fluctuations can exceed limits set by appropriate standards. New lamp types such as compact fluorescent lights (CFLs) are less sensitive to voltage fluctuations as their flicker characteristics are considerably different compared to those of the traditional incandescent lamp. These differences could support the moderation of the present voltage fluctuation and flicker standards and hence the associated limits. The potential detrimental effects on electrical equipment which may be caused by relaxation of these limits should be investigated before any changes to the present standards take place. The impact of voltage fluctuations ...


Magnetic Circuit Of A Synchronous Reluctance Motor, P P. Ciufo, D. Platt, B S. P Perera Jan 2014

Magnetic Circuit Of A Synchronous Reluctance Motor, P P. Ciufo, D. Platt, B S. P Perera

Dr Philip Ciufo

This paper presents a model of the magnetic circuit for an axially laminated synchronous reluctance motor. The basis of the modelling technique is the determination of a value for an equivalent ``q-channel'' reluctance. This reluctance contains all the effects of paths available to q-axis flux through the rotor body. Expressions for the distribution of airgap and other motor fluxes have been developed from basic analyses involving mmf and continuity of flux. The foundations of all of these expressions are the physical parameters of the motor. The equations developed have been applied to a 370 W motor and the results from ...


Simulation Model Of A Grid-Connected Single-Phase Photovoltaic System In Pscad/Emtdc, Brian K. Perera, Sridhar R. Pulikanti, Philip Ciufo, Sarath Perera Feb 2013

Simulation Model Of A Grid-Connected Single-Phase Photovoltaic System In Pscad/Emtdc, Brian K. Perera, Sridhar R. Pulikanti, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

In this paper, a complete simulation model of a grid-connected single-phase two-stage photovoltaic (PV) system with associated controllers is presented. The simulation model is developed in PSCAD/EMTDC simulation program. The component models of the grid-connected PV system include a PV array, a dc-dc boost converter, a voltage source converter (VSC) and an LCL filter. Components of the LCL filter, the dc-link capacitor of the VSC and the inductor of the dc-dc boost converter are established theoretically and that are used in modelling the grid-connected PV system. The control architecture of the presented system incorporates a synchronous reference frame phase-locked-loop ...


Comparison Of Methodologies For Assessment Of Harmonic Current Emission Limits For Large Installations Connected To Lv Networks, Biyanvilage Perera, Sarath Perera, Philip Ciufo, Victor J. Gosbell Feb 2013

Comparison Of Methodologies For Assessment Of Harmonic Current Emission Limits For Large Installations Connected To Lv Networks, Biyanvilage Perera, Sarath Perera, Philip Ciufo, Victor J. Gosbell

Dr Philip Ciufo

With the proliferation of large, disturbing installations (loads and distribution generators) connected to public low voltage networks, managing the harmonic voltage levels in the network has become a key concern to distribution network service providers (DNSPs). Therefore, it is important that DNSPs limit the harmonic current emission by individual installations. This paper reviews a number of methodologies that exist in the current technical literature in relation to the assessment of harmonic current emission limits for disturbing installations connected to the public LV network. Application of these methodologies is demonstrated through a case study on a test network. The study shows ...


Impact Of Mains Connected Three-Phase Induction Motor Loading Levels On Network Voltage Unbalance Attenuation, Upuli Jayatunga, Sarath Perera, Philip Ciufo Feb 2013

Impact Of Mains Connected Three-Phase Induction Motor Loading Levels On Network Voltage Unbalance Attenuation, Upuli Jayatunga, Sarath Perera, Philip Ciufo

Dr Philip Ciufo

Voltage unbalance (VU) in power systems should be managed in a systematic manner in order to minimise its adverse effects on both customer equipment and supply utilities. It is a well known fact that three-phase induction motor performance can be significantly affected in the presence of supply voltage unbalance. It is also known that three-phase induction motors can help to reduce pre-existing network voltage unbalance levels. Recently undertaken research aligned with IEC/TR 61000-3-13:2008 Technical Report on voltage unbalance management (emission allocation and emission assessment) have quantified the contribution made by induction motors to the net voltage unbalance at ...


Flicker Propagation Analysis In Distribution Networks With Embedded Generation, D Perera, L Meegahapola, S Perera, P Ciufo Feb 2013

Flicker Propagation Analysis In Distribution Networks With Embedded Generation, D Perera, L Meegahapola, S Perera, P Ciufo

Dr Philip Ciufo

Embedded generators such as wind generators can produce observable voltage fluctuations during variable wind conditions hence flicker. The flicker produced by such intermittent and fluctuating generating sources can propagate to other parts of the distribution network while creating power quality issues in distribution feeders. This study presents a flicker emission analysis for a doubly-fed induction generator (DFIG) based wind farm and investigate the pertinent factors which influence flicker propagation and attenuation in distribution feeders. Study has shown that voltage fluctuations are significantly influenced by the attenuation characteristics of various load types (i.e. constant power, impedance and current loads) connected ...


A Study On The Suitability Of Cable Models To Simulate Switching Transients In A 132 Kv Underground Cable, Muhamad Zalani Daud, P Ciufo, S Perera Dec 2012

A Study On The Suitability Of Cable Models To Simulate Switching Transients In A 132 Kv Underground Cable, Muhamad Zalani Daud, P Ciufo, S Perera

Dr Philip Ciufo

Switching transients resulting from the energisation of high voltage cable systems may have a significant effect on both the cables being switched as well as the power system components in the vicinity. The impacts of these transients on such cables are measured based on the stress arising as a result of the voltage and current peaks and the frequency of oscillatory transients. These quantities are typically obtained from a simulation by using a suitable cable model, normally with the capability to predict the transient behaviour in the range up to several 10 kHz. To obtain a cable model that enables ...