EPECentre: Conferences and Presentations
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Item Open Access Investigating the impact of ferrite magnetic cores on the performance of supercapacitor assisted surge absorber (SCASA) technique(IEEE, 2019) Kularatna N; Steyn-Ross DA; Silva Thotabaddadurage, Dr. SadeeshvaraSupercapacitor assisted surge absorber (SCASA) is a patented technique developed by the University of Waikato. One noticeable attribute of this design is the inclusion of a coupledinductor which improves its capability of surge absorption. This paper mainly focuses on investigating the usability of ferrite iron for the core of the coupled-inductor, and attempts to explain how to minimize the effects of a negative voltage peak that arise during SCASA operation. Four ferrite cores with different geometries and material compositions (W-ferrite and J-ferrite) are subjected to 6.6 kV surge hits. Experimental outcomes demanded the need of inserting air-gaps inside these ferrite toroids. High magnetic permeability of ferrite results in a low energy storage capability; this limits their suitability in surge absorption related applications. To overcome the issues of high permeability we modified the cores with thin cuts through the surfaces. Experimental work is facilitated by lightning surge simulators (LSS-6110 and LSS-6230) coupled with the utility main to generate surge waveforms defined by the IEEE C62.41. The analysis of test results encourages us to justify the gappedcore approach, and to further verify, performance of SCASA is empirically compared for both powdered-iron cores and modified ferrite cores using international protocols of UL-1449.Item Open Access Permeance based model for the coupled-inductor utilized in the supercapacitor assisted surge absorber (SCASA) and its experimental validation(IEEE, 2020) Kularatna N; Steyn-Ross DA; Silva Thotabaddadurage, Dr. SadeeshvaraTransient-surge absorption capability of small/low cost supercapacitors (SCs) is already published. SCASA is a patented technique that led to the development of a high performance commercial surge protector which adheres to UL-1449 3rd edition test protocols. The commercial implementation comprises a coupled-inductor, two metal oxide varistors (MOVs) and a SC sub-circuit. This paper presents a permeance based model for the coupled-inductor of SCASA topology in predicting its operation under contrasting voltage conditions. In validating the circuit operation with regard to its surge absorption capability versus 50 Hz AC power transfer, a lightning surge simulator (LSS-6230) was utilized. We discuss this comparison based on the standard IEEE C62.41 surge waveforms up to a maximum of 6.6 kV.Item Open Access Supercapacitor assisted surge absorber (SCASA) technique: selection of magnetic components based on permeance(IEEE, 2021) Kokuhennadige S; Fernando J; Kularatna N; Steyn-Ross DA; Silva Thotabaddadurage, Dr. SadeeshvaraSupercapacitors help building long time constant resistor-capacitor circuits. This property helps them withstand high voltage transient surges and dissipate transient energy in the resistive element of the circuit without exceeding the supercapacitor’s DC voltage rating, which is usually between 2.5 to 4 V. SCASA is a patented technique, which was commercialized within the last five years. Successful implementation of this circuit topology, despite its simplicity, is quite dependent on the selection of the core of the coupled inductor utilized. This paper provides the essential details of the process of selecting the core for the magnetic component required, with a brief comparison of SCASA technique with a traditional surge protector, without any supercapacitors.Item Open Access An Analogy between Linguistics and Science: A comparative study(2015) Silva Thotabaddadurage, Dr. SadeeshvaraItem Open Access Impact of Climate change on Tourism in Sri Lanka: An Investigation(2015) Silva Thotabaddadurage, Dr. SadeeshvaraTourism is the act and process of spending time away from home in pursuit of recreation, relaxation, and pleasure, while making use of the commercial provision of services. It is further identified as a product of modern social arrangements. On the other hand, climate change refers to a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods. The objective of this paper is thus to investigate negatives of climate change on Sri Lankan tourism while pointing out how tourism itself becomes a culprit of unconventional climatic transformations. Therefore,the research problem that is intended to answer through this study is “How feasible it is to establish a climate friendly tourism in Sri Lanka?” This study was mainly conducted in three stages. In the initial stage of data collecting, primary methodology in focus is to delve in to several unhealthy climatic conditions especially in relation to Sri Lankan tourist industry and to gather facts such as their causes, their severity, their impact and etc. Next, some insight was put on to identify and analyze how tourism itself is responsible in causing such conditions. Thus, several ecofriendly methodologies that can be practically implemented were introduced in some depth while constructing a realistic supply chain that highly favors the environment. In the final concluding stage, obvious possibility of climate friendly tourism was seen on the basis of three important concepts: “Avoidance, Substitution and Offsetting”. These conclusions are purely based on a qualitative analysis where an attempt is taken to introduce techniques of optimization within tourist industry for a better economy.Item Open Access Literature as an inspiration for scientific thinking: An Investigation(2015) Silva Thotabaddadurage, Dr. SadeeshvaraItem Open Access Mind the Gaps(University of Canterbury. Electrical and Computer Engineering, 2016) Lapthorn, Andrew; Pandey, Shreejan; Sorez, MarionThe word “diversity” is well adopted and celebrated by globally successful companies including Google and Apple who claim that diversity inspires innovation. The New Zealand electricity supply industry supports a number of initiatives that aims to address gender diversity, and increase the number of high achieving electrical engineering graduates. However, the desire to enhance workforce capability by encouraging diversity in New Zealand’s electricity industry is not yet fully realised. The gender imbalance is a noticeable issue across all sectors, and anecdotal evidence suggests that there is a void of young engineers to acquire knowledge from experienced senior professionals and smoothly transition into senior roles. Understanding the demographic profile of electrical engineers derived from census data helps to identify any gaps that need to be addressed. Tertiary enrolment demographic trends for the Electrical and Electronic Engineering (EEE) degree specialisation can be referred to as a proxy for what the future demographic profile of the electricity industry may look like. This paper analyses and discusses the demographic trends of professional electrical engineers and tertiary students who have completed electrical and electronic related qualifications at universities and polytechnics. Targeted areas that require attention and investment are identified and discussed.Item Open Access Draft Guideline for the connection of smallscale inverter based distributed generation(2016) Strahan, RichardItem Open Access Update: Guide for the connection of smallscale inverter-based distributed generation(2016) Strahan, RichardItem Open Access Systems to Implement Demand Response in New Zealand(2014) Strahan, Richard; Miller, AllanItem Open Access Systems to Implement Demand Response in New Zealand(2014) Strahan, Richard; Miller, Allan; Tahau, QuintinAccording to the Federal Energy Regulatory Commission, Demand Response (DR) is defined as: “Changes in electric usage by end-use customers from their normal consumption patterns in response to changes in the price of electricity over time, or to incentive payments designed to induce lower electricity use at times of high wholesale market prices or when system reliability is jeopardized.” In the US, experience with regional electricity markets suggests that active DR is crucial to both power system reliability and market efficiency. Accordingly, efforts to enable demand-side participation in the US are providing significant opportunities for end-customers, load serving entities, and independent system operators. In New Zealand, a number of DR initiatives exist or are coming online. Given the importance of DR initiatives and systems to enable participation in the demand side of the market, the purpose of this paper is to provide a detailed understanding of the various systems already installed, and potentially required, to implement DR in New Zealand. Types of DR considered include interruptible load, Transpower’s demand response initiatives, demand side bidding and forecasting, dispatchable demand, and ripple control. This paper also reviews which groups of market participants are using DR, and for what purpose. Currently, most DR is incentive based, but the deployment of smart meters at consumers’ premises may lead to significant adoption of price based DR, such as initiatives to introduce time of use and peak pricing to domestic users. Home Energy Management Systems (HEMS) have been defined as any product or service that monitors, controls, or analyzes energy in the home, and may be utility or non-utility based. HEMS and the initiatives mentioned form a rapidly emerging fabric of DR systems in NZ.Item Open Access Trends in industrial electric motor usage and potential impact on energy consumption(2012) Strahan, RichardItem Open Access Optimising Reserve for Contingencies while Explicitly Including Response Speed of Reserve Providers(2020) Schipper, JoshNoneItem Open Access Review of Distributed Generation Interconnection Standards(2014) Schwartfeger, Luke; Santos-Martin, David; Wood, Alan; Watson, Neville; Miller, AllanGrid operators, worldwide, are experiencing higher distributed generation penetration levels. This new paradigm is starting to show its effects and in order to maintain the safety and reliability of the network, most distribution system operators are adopting international standards or defining their own. Besides available international standards, a large variety of national or local requirements appear to give an answer to those local necessities. These local factors are highly dependent on the geography, grid structure, type of technology and the amount of current penetration level of distributed generation. In New Zealand, the recent rapid uptake of distributed generation, in particular for photovoltaics, and the diversity of distribution companies’ guidelines, along with the vision of a future common framework for New Zealand has inspired the review of all international standards and a cross comparison with local guide lines has been performed. The purpose of this analysis is to build a picture of these standards and give a brief insight into the current stance the national distribution companies have via their policies. Presented at the 2014 EEA conferenceItem Open Access Electric Vehicles in New Zealand: Technologically challenged(2013) Lemon, Scott; Miller, AllanIn conclusion, the key barrier to improved EV performance, lower costs and increased market uptake is their technology and, in particular, current generation lithium-ion batteries. Unless existing battery chemistries are further developed and specific energy, power and lifespan characteristics are improved, the range and overall life of electric vehicles will remain inferior to that of internal combustion vehicles. These developments are likely to occur through research by the leading battery technology manufacturers in South Korea and Japan. The actual integration of these battery systems and mass manufacturing of EVs will occur predominantly in the United States and Japan. Consequently, in the short- to medium-term New Zealand will have wait for large manufacturers in other countries to increase EV production and decrease local prices through the economies of scale. However, New Zealand should start preparing now for the introduction of EVs. This includes the development of smart grid technology, increased renewable integration for charging, and real-world research into the potential of vehicle-to-grid technology for facilitating increased integration of these resources into the grid. Presented at the 2013 EEA conferenceItem Open Access Electrical Vehicle Storage Technologies and Range(2017) Landon-Lane, Leatham; Miller, Allan; Marshall, Aaron; Gaynor, PaulInformation regarding electric vehicles is not always clearly and accurately portrayed to the general public. This paper provides a holistic view of the worldwide vehicle market, focussing on the current and future capabilities of vehicles powered by different fuel sources. The types of vehicles chosen for case studies in this paper are: Internal Combustion Engine (ICE), Hydrogen Fuel Cell (HFC), and Battery Electric Vehicles (BEVs). Factors considered include energy storage density, efficiency, upfront and running costs and scope for improvement in each of the vehicle technologies. The primary purpose of this paper is to inform the reader of the progress made with alternatively fuelled vehicles, what improvements will need to be made in order to make them more like-for-like replacements for ICE vehicles, and the implications an increased market share of each type may have on national and local infrastructure. The major findings from this paper show that BEVs are a more practicable solution than HFC vehicles for replacing ICE vehicles. BEV sales are increasing rapidly due to falling battery costs, with future sales increases likely to be driven by lower cost and higher energy density batteries. Improvements in battery technology are likely to be limited to Li-ion in the short term, with metal-air batteries offering potentially higher energy densities at a lower cost, but technical difficulties are preventing current use. In order to be equivalent to ICE vehicles, BEVs require increased range and faster charging times, which are both achievable without the need for battery swapping. Presented at the 2017 EEA conferenceItem Open Access Technology Choices for an Evolving Power System(2019) Mukhedkar, RadnyaElectrification of processes and transition towards 100% renewable generation is considered instrumental for achievement of a low emission future and this can be fuelled by enabling technologies. New Zealand and Australia, like any other countries, are grappling with achieving this goal while transitioning from a legacy electrical network, with the constraints it imposes, by making incremental enhancements. The facilitating technologies; for instance power electronic converters and digital systems (which include a combination of control systems, distributed sensors, communication network and mathematical models) introduce the necessary flexibility and controllability within the power system [23-24]. There are a number of technology choices available so as to engineer an effective transition with scarce resources. This paper will analyse some of the alternative technologies and solutions considering the performance at the point of connection (including low inertia power systems), designing for efficiency and reliability [22-25]. The alternatives will include energy sources and storage; AC and DC transmission; aggregated and distributed controls. Presented at the 2019 EEA conferenceItem Open Access There is potential for pumped hydro energy storage in New Zealand(University of Canterbury, 2019) McQueen, DougalThe decarbonisation of New Zealand’s energy system will increase demand for electricity at the same time as fossil fuelled generation is phased out. Maintaining balance in the power system will become increasingly difficult as more variable generation is integrated and it is unlikely that the existing generation portfolio, with any additional generation, and demand side management will allow sufficient control. It will be necessary to increase energy storage and generation capacity. Pump Hydro Energy Storage (PHES) is the most cost effective mature energy storage technology; comprising 95% of active energy storage worldwide. PHES has relatively low carbon emissions, a high energy storage to investment ratio and long plant lifespans. However, costs and risks are project specific reflecting the range of scheme designs and dependence on geomorphology. Further, the time to develop PHES schemes is long and have environmental and other impact that are complex to assess. There is a lot to be gained from systematic evaluation of resources and optimisation of scheme designs. Here an overview of the technology, summary of previously proposed projects, and results from a search for a variety of scheme types is presented. To support resource evaluation, a GIS based evolutionary algorithm is developed and used to find a quasi-optimal upper reservoir location for a scheme using Lake Roxburgh as the lower reservoir and to identify reservoir locations for a closed loop scheme. This work is part of the GREEN Grid project (officially titled “Renewable Energy and the Smart Grid”) funded by Ministry Business Innovation and Employment (MBIE) in New Zealand and co-funded by Transpower and the Electricity Engineers’ Association (EEA). Presented at the 2019 EEA conferenceItem Open Access Management of Distributed Generation Using DGHost in NZ(2018) McNab, Sharee J.; Lemon, S.; Crownshaw, Tim; Strahan, Richard; Miller, Allan