Browsing by Author "Gunasekera, S"

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item: Conference-Full-text
Modeling and sizing of hybrid energy storage system for virtual synchronous generator
(IEEE, 2021-07) Wijetunge, SV; Gunasekera, S; Gamage, J; Pathirana, CD; Bolonne, S; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Renewable energy sources (RESs) play a major role in the modern power system to meet the increasing demand and to reduce environmental effects. But they are unable to perform frequency regulation resulting in higher frequency deviations with higher integration of RESs. To overcome this problem power converters are modified as synchronous generators using proper control mechanisms called as Virtual Synchronous Generators (VSGs). Energy Storage Systems are required to absorb and deliver excess energy. We have used a battery/ultracapacitor hybrid energy storage system (HESS) to achieve this. Power allocation for the two storage units is modeled such that fast-varying power fluctuations are compensated by ultracapacitor (UC) and low frequency power fluctuations are compensated by the battery. This is achieved by emulating the inertia by the ultracapacitor and emulating reheat turbine model, droop control etc. by the battery. Some research produces the modelling details of HESS but not the sizing considering required performance. To fulfil this research gap sizing of the HESS is presented through this research paper. Eventually, the proposed system was implemented and simulated in MATLAB Simulink. Results were analyzed to verify the proposed concept for different cases to prove that it gives outputs similar to conventional synchronous generator.
item: Conference-Full-text
Sri Lankan graphite making the space elevator possible
(2013-11-19) Samaranayake, BGLT; Gunasekera, S; Kumarasinghe, AKR; Kottegoda, NS
A metal catalyst free, low cost process of manufacturing carbon nanotubes (CNT) using Sri Lankan graphite as anode and cathode, in the absence of external cooling, in an inert gas atmosphere is presented in this paper. The CNT yield has been analyzed using High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM) and Raman spectroscopy.
item: Thesis-Abstract
Urban meeting places : An identification of the Physical, Social, and Psychological determinants of the place-type
Gunasekera, S
The relationship between man and the environment has been given considerations in the recent times. But it is yet to be understood the effective theoretical and practical phenomena of it, when designing buildings for people. Within all the places that man experiences in his day today life, "meeting place" has an importance which is not second to other places. It is important to man's social life and should be a definite entity in the built environment. Even though, people couldn't find any specifically designed places for out door public meeting activities in urban settings in Sri Lanka, some places could be found which give more opportunities to use them as people's natural meeting places, while they are engaged in their primary activities in the same place. Nowadays, designers are giving less consideration to these important entities when they design places for people. As a result, the built environment is being affected with loss of intimacy. The man-environment relationship is been divorced at many of our urban settings. This is even clear when thinking of diminishing of meeting places. In order to rebuild the bridge between those two conditions, it became of vital importance to identify the types of meeting places, the role played by them and the process how they have come in to being. In this respect this Dissertation is an approach to identify the facts, that could create an attachment to a place for meeting activities and to give a sense of belongingness to places. In other words, this is an attempt to find the Physical, Social and psychological determinants of meting places. By doing so, the author has derived a proper definition for the notion of the "Urban meeting place". It has given a basis for future researchers to look more deeper in to each and every type of meeting place and identify how the determinants of place get modified and applied to different place situations in the built environment.