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Articles 1 - 28 of 28
Full-Text Articles in Physical Sciences and Mathematics
Power Quality (Pq) Survey Reporting: Discrete Disturbance Limits, H. M. Herath, V. J. Gosbell, S. Perera
Power Quality (Pq) Survey Reporting: Discrete Disturbance Limits, H. M. Herath, V. J. Gosbell, S. Perera
Associate Professor Sarath Perera
iscrete or event type power quality (PQ) disturbances mainly include voltage sags, swells, and the transients. An extensive literature survey suggests that there is no generally accepted method for characterization of these disturbances and suitable limits are not yet found in any international standard. One of the reasons for the lack of characterization methods is the difficulty of defining suitable site indices for each discrete disturbance type. In this paper existing characterization methods are reviewed and discussed. A new generalized approach is then given to show a better way of characterizing voltage sags, swells and transients. This is followed by …
Voltage Unbalance Emission Limits For Installations: General Guidelines And System Specific Considerations, Robert Koch, Alexander Baitch, Sarath Perera, Prabodha Paranavithana
Voltage Unbalance Emission Limits For Installations: General Guidelines And System Specific Considerations, Robert Koch, Alexander Baitch, Sarath Perera, Prabodha Paranavithana
Associate Professor Sarath Perera
Guidelines for developing voltage unbalance emission limits for installations connected to EHV, HV, and MV power systems have recently been published as a technical report by the International Electrotechnical Commission (IEC). These guidelines, based on the work of Joint Working Group CIGRE/CIRED C4.103, are intended to provide a common basis for the development of similar guidelines or standards in specific countries. This paper reviews these international guidelines and the background to the development of specific recommendations made in the technical report. It also considers elements of these guidelines that may relate to specific network considerations, and therefore may be of …
Assessing The Impact Of Increased Air Conditioner Load On Power Quality In Australia, Lianne Mollier, D A. Robinson, Sarath Perera, Victor J. Gosbell, Frank Bucca
Assessing The Impact Of Increased Air Conditioner Load On Power Quality In Australia, Lianne Mollier, D A. Robinson, Sarath Perera, Victor J. Gosbell, Frank Bucca
Associate Professor Sarath Perera
Measurements of performance of existing technology air conditioner systems with regards to their impact on power quality in LV distribution systems are presented. Three types of split-phase air conditioners are studied including direct on line starting, soft starter and inverter fed units. Results of testing and subsequent calculations illustrate that the direct on line and soft starter units do not meet compliance requirements of the relevant standard, and as penetration of air conditioners increases, voltage fluctuations may become a significant problem in some LV distribution systems in Australia.
Synchronized Flicker Measurement For Flicker Transfer Evaluation In Power Systems, S. Perera, Duane Robinson, S. Elphick, D. Geddey, N. Browne, V. Smith, V. J. Gosbell
Synchronized Flicker Measurement For Flicker Transfer Evaluation In Power Systems, S. Perera, Duane Robinson, S. Elphick, D. Geddey, N. Browne, V. Smith, V. J. Gosbell
Associate Professor Sarath Perera
Voltage fluctuations caused by rapidly changing loads, such as arc furnaces, can propagate to different parts of a power system. Although the flicker level at its origin can be high, levels that are measured at other sites are subject to attenuation, a process that is influenced by fault levels, transformer impedances, line impedances, and composition of the connected loads. This paper presents the methodology, measurement results, and data analysis in relation to synchronized flicker measurements carried out in a high-voltage (HV)/medium-voltage (MV) power system which contains an arc furnace supplied by a dedicated feeder connected to the HV busbar. The …
Flicker Transfer In Radial Power Systems, Sankika Tennakoon, Lakshal Perera, D A. Robinson, Sarath Perera
Flicker Transfer In Radial Power Systems, Sankika Tennakoon, Lakshal Perera, D A. Robinson, Sarath Perera
Associate Professor Sarath Perera
Loads which exhibit continuous and rapid variations in their current can cause voltage fluctuations that are often referred to as flicker. One good example for such loads is arc furnaces which are usually fed by dedicated feeders from the high voltage busbars in transmission systems. The flicker generated from such loads will propagate to the upstream HV point of common coupling (PCC), and from there to the downstream through the transmission and sub transmission systems. This paper demonstrates how the generated flicker is propagated from the HV PCC to the downstream in radial networks exhibiting different levels of attenuation depending …
Voltage Quality Behaviour Of A Wind Turbine Based Remote Area Power System, Nishad Mendis, Kashem Muttaqi, Sarath Perera
Voltage Quality Behaviour Of A Wind Turbine Based Remote Area Power System, Nishad Mendis, Kashem Muttaqi, Sarath Perera
Associate Professor Sarath Perera
The power quality behaviour of a Remote Area Power System (RAPS) consisting of a Doubly Fed Induction Generator (DFIG), its main loads and a dummy load is presented in this paper. The dummy load is used to maintain the power balance of the system under changing wind and loading conditions. The performance of the remote area power system subject to various loading conditions has been evaluated in terms of the voltage quality, an aspect which has not received much attention in the past. The existing Distributed Generation (DG) power quality standards are taken as the basis to compare the voltage …
Power Quality Survey Factor Analysis Using Multivariable Linear Regression (Mvlr), Chandana Herath, Victor J. Gosbell, Sarath Perera, David A. Stirling
Power Quality Survey Factor Analysis Using Multivariable Linear Regression (Mvlr), Chandana Herath, Victor J. Gosbell, Sarath Perera, David A. Stirling
Associate Professor Sarath Perera
During the past two decades, there has been a considerable number of Power Quality (PQ) monitoring programs completed throughout the world. The information collected during these surveys can provide a detailed picture of the expected electrical environment help utilities to plan their future networks in relation to power quality performance. The mass of data gathered for a sample of sites of a large-scale power quality (PQ) survey of this nature has the potential to reveal good and bad influences on power quality if an appropriate procedure for analysis can be determined. If it is known which characteristics are more important …
Benchmarking Utilities For The Impact Of Voltage Sags On Customers, H. M. Herath, V. J. Gosbell, S. Perera
Benchmarking Utilities For The Impact Of Voltage Sags On Customers, H. M. Herath, V. J. Gosbell, S. Perera
Associate Professor Sarath Perera
Most utilities have increased their focus on voltage sags as the sags account for vast majority of recorded equipment trips. Although these events are not necessarily the most frequent, they have a tremendous economic impact on end-users. The process of benchmarking customer voltage sag levels generally requires voltage sag monitoring data for a period of minimum one year. This data can then be quantified to relate voltage sag performance with standardized limits for acceptable performance. This work suggests a methodology for benchmarking the impact of voltage sags on customers of different utilities by means of a three stage reporting procedure …
The Application Of Iec 61000-3-6 To Mv Systems In Australia, Victor J. Gosbell, D A. Robinson, Sarath Perera, Alex Baitch
The Application Of Iec 61000-3-6 To Mv Systems In Australia, Victor J. Gosbell, D A. Robinson, Sarath Perera, Alex Baitch
Associate Professor Sarath Perera
IEC 61000-3-6 [1] comprises a number of stages and tests to determine harmonic emission allowances for customers connected to MV or HV networks. Of particular importance is the section concerning loads distributed along a feeder, each having a different fault level. Although a common situation, the treatment given in the IEC standard is poorly described, being largely illustrated by one atypical example. This allows simplifying assumptions to be made which are invalid in practical cases. This paper outlines a more general approach that is relatively easy to apply.
A Transient Index For Reporting Power Quality Surveys, Victor J. Gosbell, Sarath Perera, D A. Robinson, Chandana Herath
A Transient Index For Reporting Power Quality Surveys, Victor J. Gosbell, Sarath Perera, D A. Robinson, Chandana Herath
Associate Professor Sarath Perera
Impulsive transients are often blamed for the destruction of customer appliances. Advances in Power Quality (PQ) monitors will soon make it feasible to incorporate impulsive transients into routine power quality surveys. This paper considers how the transient events captured over a period at many sites may be reported in a simple but useful manner. The paper first summarizes a recent publication by some of the authors, which attempt to give a complete framework for the analysis of utility PQ data. This framework provides a basis for evaluating existing transient characterization practices as well as for the proposed new transient index …
Support Of Distribution System Using Distributed Wind And Pv Systems, Kai Zou, Ashish P. Agalgaonkar, Kashem Muttaqi, Sarath Perera, N Browne
Support Of Distribution System Using Distributed Wind And Pv Systems, Kai Zou, Ashish P. Agalgaonkar, Kashem Muttaqi, Sarath Perera, N Browne
Associate Professor Sarath Perera
The application of renewable distributed generation (DG) could be considered as an alternative approach for distribution system expansion planning not only to reduce power loss and carbon emission, but also to improve system voltage profile. This paper investigates technical aspects relatedto voltage support and loss reduction in distribution systems with distributed wind and solar generation. The probabilistic wind, solar, and load models have been developed in order to address uncertain nature of wind speed, solar radiation, and load demand. Investigations have been carried out using Monte Carlo based probabilistic load flow analysis to estimate the probability distributions of system state …
Simulation Of Hts Saturable Core-Type Fcls For Mv Distribution Systems, S B. Abbott, Duane Robinson, S Perera, F A. Darmann, C J. Hawley, T P. Beales
Simulation Of Hts Saturable Core-Type Fcls For Mv Distribution Systems, S B. Abbott, Duane Robinson, S Perera, F A. Darmann, C J. Hawley, T P. Beales
Associate Professor Sarath Perera
The design principles and performance characteristics of a prototype high-temperature superconductor saturable magnetic core-type fault current limiter are described. These are based on a distribution network service provider feasibility specification that included the footprint and regulatory requirements for limiting fault currents. Time-domain simulations using PSCAD/EMTDC are given to illustrate specific applications and the transient behavior of the different distribution system configurations are investigated.
Power Quality Data Analysis Using Unsupervised Data Mining, Ali Asheibi, David A. Stirling, Sarath Perera, D A. Robinson
Power Quality Data Analysis Using Unsupervised Data Mining, Ali Asheibi, David A. Stirling, Sarath Perera, D A. Robinson
Associate Professor Sarath Perera
The rapid increase in the size of databases required to store power quality monitoring data has demanded new techniques for analysing and understanding the data. One suggested technique to assist in analysis is data mining. Data mining is a process that uses a variety of data analysis tools to identify hidden patterns and relationships within large samples of data. This paper presents several data mining tools and techniques that are applicable to power quality data analysis to enable efficient reporting of disturbance indices and identify network problems through pattern recognition. This paper also presents results of data mining techniques applied …
Dynamic Modelling Of Hydroelectric Turbine-Generator Unit Connected To A Hvdc System For Small Signal Stability Analysis, Yin Chin Choo, Ashish P. Agalgaonkar, Kashem Muttaqi, Sarath Perera, Michael Negnevitsky
Dynamic Modelling Of Hydroelectric Turbine-Generator Unit Connected To A Hvdc System For Small Signal Stability Analysis, Yin Chin Choo, Ashish P. Agalgaonkar, Kashem Muttaqi, Sarath Perera, Michael Negnevitsky
Associate Professor Sarath Perera
This paper presents the linearised small-signal dynamic modelling of hydroelectric turbine-generator (TG) unit with CIGRE first high-voltage direct current (HVDC) benchmark system in the synchronously rotating D-Q reference frame for small-signal stability analysis. The interaction behaviour between the hydroelectric unit and the dynamics and control of HVDC system is investigated utilising eigen-analysis,participation factor analysis and by conducting sensitivity studies. The computation of eigenvalues and eigenvectors for small signal stability analysis provides an invaluable insight onto the power system dynamic behaviour by characterising the damping and frequency of the system oscillatory modes. Theconsequences of different operating conditions, such as active and …
Sources Of Error In Unbalance Measurements, Victor J. Gosbell, H Herath, Sarath Perera, D A. Robinson
Sources Of Error In Unbalance Measurements, Victor J. Gosbell, H Herath, Sarath Perera, D A. Robinson
Associate Professor Sarath Perera
The paper aims to assess sources of error in attempting to meet standards for the measurement and reporting of negative sequence voltage unbalance. This is of importance when making use of low performance instrumentation where three difficulties may arise: (i) rms voltages rather than the fundamental is used; (ii) the magnitude but not the phase of line-neutral voltages are available; and (iii) voltage values are averaged over a period longer than standards require. The presence of harmonics at normal levels is shown to give negligible error on unbalance calculations. When lineneutral voltages are used, and zero sequence is present, the …
Response Of Mains Connected Induction Motors To Low Frequency Voltage Fluctuations From A Flicker Perspective, Sankika Tennakoon, Sarath Perera, D A. Robinson
Response Of Mains Connected Induction Motors To Low Frequency Voltage Fluctuations From A Flicker Perspective, Sankika Tennakoon, Sarath Perera, D A. Robinson
Associate Professor Sarath Perera
In radial power systems flicker transfer from a higher voltage level (upstream) to a lower voltage level (downstream) is seen to be significantly affected by the downstream load composition. Industrial load bases containing mains connected induction motors are known to be effective in the flicker attenuation process compared to residential load bases containing passive loads. For better understanding of the flicker attenuation influenced by induction motors their dynamic behaviour has to be closely investigated under fluctuating supply conditions. This paper presents the methodology and results of investigations undertaken to examine the response of an induction motor to small perturbations in …
Analysis Of Network Asymmetry Of Interconnected 66kv Sub-Transmission Systems In Relation To Voltage Unbalance, Prabodha Paranavithana, S. Perera, Danny Sutanto
Analysis Of Network Asymmetry Of Interconnected 66kv Sub-Transmission Systems In Relation To Voltage Unbalance, Prabodha Paranavithana, S. Perera, Danny Sutanto
Associate Professor Sarath Perera
The levels of voltage unbalance that exist in some interconnected sub-transmission networks in Australia has been observed to be above the code requirements (e.g. 1% in Victoria). There is a perception that these high levels arise as a result of asymmetrical loads. However, it is identified that the network asymmetry in relation to transmission lines also play a significant role in the lead up to this situation, employing an interconnected 66kV sub-transmission system as the study case. The individual transmission lines of the study network are analysed in order to observe their possible influence arising as a result of line …
Saidi Minimization Of A Remote Distribution Feeder, Kai Zou, Wickramaarachchi W. Keerthipala, Sarath Perera
Saidi Minimization Of A Remote Distribution Feeder, Kai Zou, Wickramaarachchi W. Keerthipala, Sarath Perera
Associate Professor Sarath Perera
Distribution system reliability assessment is an important part of distribution system operation and planning. This paper presents some approaches taken to minimize the SAIDI (System Average Interruption Duration Index) for a remote distribution feeder in an 11kV distribution system. Resulting from unavailability of alternative backup supplies from the other adjacent feeders, distributed generators (DG) can be used as backup supplies in this case. Coordinating distribution automation (DA) system with DGs, the restoration area can be made larger and the outage time can be shorter, consequently, the distribution system reliability can be improved significantly. In this paper, factors affecting SAIDI are …
Power Quality Waveform Generator Based On The Csound Software Sound Synthesizer, J. P. Braun, V. J. Gosbell, S. Perera
Power Quality Waveform Generator Based On The Csound Software Sound Synthesizer, J. P. Braun, V. J. Gosbell, S. Perera
Associate Professor Sarath Perera
Power quality investigations in the laboratory often require waveform generators capable of recreating the various disturbances present in an electrical system. These sources of waveforms are generally based on arbitrary waveform generators (AWG) because of the great flexibility they offer. However, AWGs are generally not well suited for time varying waveforms because of the limited size of their memory. To circumvent this limitation, a real time waveform synthesizer is required, but their applicability is generally limited by cost. This paper presents the use of CSound, a software sound synthesizer to achieve this aim in a cost effective manner. This paper …
Harmonic Allocation Constant For Implementation Of As/Nzs 61000.3.6, D A. Robinson, Victor J. Gosbell, Sarath Perera
Harmonic Allocation Constant For Implementation Of As/Nzs 61000.3.6, D A. Robinson, Victor J. Gosbell, Sarath Perera
Associate Professor Sarath Perera
Allocation of equal harmonic emission rights to MV customers having the same maximum demand is a key concept in the new Australian harmonic standard AS/NZS 61000.3.6 [1]. Some difficulty can arise with the application of the standard when customers are spread out along a feeder with significantly different fault levels. One proposed method of overcoming this problem is to reduce the allocation as the square root of the fault level [2]. This method requires the calculation of an allocation constant that is applied to all customers connected to the same zone substation. This paper gives a methodology for calculating the …
Harmonic Allocation To Aggregated Regions Within A Transmission Network, Timothy J. Browne, Victor J. Gosbell, Sarath Perera
Harmonic Allocation To Aggregated Regions Within A Transmission Network, Timothy J. Browne, Victor J. Gosbell, Sarath Perera
Associate Professor Sarath Perera
Utilising the standard AS/NZS61000.3.6 to carry out a harmonic allocation to a load in a transmission system requires detailed knowledge of the location and magnitude of every future load. Given that the size of the load at a bus in a transmission system could conceivably be from zero up to around thirty percent of the fault level, such knowledge is unlikely to be available with any degree of certainty. This paper proposes an allocation policy which reduces the effect of load uncertainty, by allocating harmonic emission levels to areas comprising buses which are electrically close. Possible techniques are demonstrated using …
Flicker Propagation In Interconnected Power Systems, S. Tennakoon, S. Perera, Danny Sutanto
Flicker Propagation In Interconnected Power Systems, S. Tennakoon, S. Perera, Danny Sutanto
Associate Professor Sarath Perera
Voltage fluctuations leading to lamp flicker can propagate from the point of origin to various parts of the power system with some attenuation depending on the system impedances and load composition. Field measurements and theoretical studies suggest that the industrial loads containing large proportions of induction motors assist in attenuating flicker compared to residential loads consisting ofpassive devices. This paper describes a frequency domain approach which can be used to determine the propagation ofvoltagefluctuations when there are induction motor loads in the vicinity of the disturbing load. The method involves linearization of the network in d-q domain to evaluate various …
Characterisation Of High Temperature Superconducting Coils, Christopher David Cook, Sarath Perera, Thomas Hardjono
Characterisation Of High Temperature Superconducting Coils, Christopher David Cook, Sarath Perera, Thomas Hardjono
Associate Professor Sarath Perera
Some power engineering systems, such as efficient energy storage for power quality improvement, can be potentially made more efficient if implemented with large coils made of high temperature superconductors (HTS). However, the losses of HTS coils carrying AC current limit their usage in practical applications. It has been shown previously that a thin pancake coil with relatively large diameter can be modelled as straight tapes arranged in a face-to-face stack. This paper reviews those results. In addition, measurements on a more realistic larger HTS coil were carried out. It is shown that the model assumptions provide less accurate results for …
Optimisation Of Distributed Generation Units And Shunt Capacitors For Economic Operation Of Distribution Systems, Kai Zou, Sarath Perera, Kashem Muttaqi, Ashish P. Agalgaonkar
Optimisation Of Distributed Generation Units And Shunt Capacitors For Economic Operation Of Distribution Systems, Kai Zou, Sarath Perera, Kashem Muttaqi, Ashish P. Agalgaonkar
Associate Professor Sarath Perera
The integration of Distributed Generation (DG) units and shunt capacitors can be considered as an alternative approach for distribution system expansion planning not only to improve power supply quality and reliability, but also to defer major system updates. In this paper, the techno-economic issues of distribution system expansion planning with optimal sizing and siting of DG units and shunt capacitors are addressed. The minimisation of overall investment cost with the integration of DG units and shunt capacitors is assessed with the consideration of supply quality, reliability and energy loss. A new planning methodology by using Particle Swarm Optimisation (PSO) is …
Supply Current Charactersistics Of Modern Domestic Loads, Sean T. Elphick, Sarath Perera, Philip Ciufo
Supply Current Charactersistics Of Modern Domestic Loads, Sean T. Elphick, Sarath Perera, Philip Ciufo
Associate Professor Sarath Perera
The domestic load is considerably different to that seen 10 to 15 years ago. It has evolved significantly in terms of consumption and characteristics. In addition to traditional resistive and refrigeration type loads, the modern domestic load is now likely to contain a variety of sophisticated devices mostlypowered and controlled by power electronics. This paper examines the power quality characteristics of the modern domestic load. Laboratory testing and mathematical analysis is used to quantify and predict the behaviour of loads operating individually and in parallel. Specifically examined is thebehaviour and variation in harmonic current magnitudes across a variety of loads.
Behavioural Modelling Of High Temperature Superconducting Wires And Coils For Power Engineering Applications, Thomas Hardjono, Christopher David Cook, Sarath Perera
Behavioural Modelling Of High Temperature Superconducting Wires And Coils For Power Engineering Applications, Thomas Hardjono, Christopher David Cook, Sarath Perera
Associate Professor Sarath Perera
Many aspects of the behaviour of high temperature superconducting (HTS) wires are well understood for dc applications. However, models of HTS suitable for use in circuit analysis by power engineers designing HTS applications are not readily available. This paper describes the initial development of suitable models for HTS wire. The V-I characteristics for wires carrying dc transport current can be empirically determined using a power law V=kIn. Experimentally measured V-I characteristics are fitted using the above power law. This enables the simulation of the behaviour of Bi-2223/Ag wire using the well-known circuit simulator PSpice. Other factors affecting the dc critical …
Conditions For The Assessment Of The Harmonic Compliance Of An Installation, Timothy J. Browne, Sarath Perera, Victor J. Gosbell
Conditions For The Assessment Of The Harmonic Compliance Of An Installation, Timothy J. Browne, Sarath Perera, Victor J. Gosbell
Associate Professor Sarath Perera
Methods of allocating harmonic emission limits to customer installations have evolved considerably, as evidenced by the development of harmonic guides such as IEEE-519 and IEC/TR 61000-3-6. However, there is only limited consensus on appropriate techniques validating compliance of installations with those limits. Existing techniques are reviewed and related problems are examined. Conditions which acceptable tests of compliance should meet are proposed.
Harmonic Survey Of An Mv Distribution System, Victor J. Gosbell, Damian Mannix, D A. Robinson, Sarath Perera
Harmonic Survey Of An Mv Distribution System, Victor J. Gosbell, Damian Mannix, D A. Robinson, Sarath Perera
Associate Professor Sarath Perera
The harmonic survey of a medium voltage distribution system involves three major aspects: (i) the choice of harmonic monitor, (ii) the choice of monitoring site, (iii) processing and presentation of results. As well as a discussion of the methodology for these aspects, the paper will discuss the harmonic levels measured, the minimum survey requirements for finding useful data and the harmonic parameters of residential, commercial and industrial loads.