Master of Science in Electrical Installations

Permanent URI for this collectionhttp://192.248.9.226/handle/123/56

Browse

Now showing 1 - 20 of 79

item: Thesis-Abstract
Feasible study on the power quality issues of voltage variation and harmonics due to PV penetration in LVDN : a case study in Negombo LVDN Sri Lanka
(2024) Saravanapavan, S; Rodrigo, WDAS
Renewable energy resources are encouraged all over the world to have a green power generation to avoid global warming due to conventional energy sources. As one of a sustainable power source, solar photovoltaic system is considered in micro grid and domestic solar system. Domestic solar systems have a rapid growth in Sri Lanka since last decade and they are connected with the existing low voltage distribution network. Therefore, it causes power quality issues with increasing PV penetration in LVDN. The common PQ issue arising from PV penetration is the voltage rise. Therefore, a LVDN with voltage rise issue in Negombo, Sri Lanka was selected for the case study of this research. This research focused on a LVDN with low active power existence and high feeder resistance where the voltage rise is due to feeder resistance with increasing PV penetration. This study considered power quality issues of voltage violation, harmonic analysis and power factor violation in the selected LVDN. Analysis of another LVDN with different transformer capacity was also summarized in this study. The mitigation techniques of active network management and network reinforcement were applied to the LVDN and the response was analyzed. The harmonic results were insignificant with voltage violation. And when the voltage rise was mitigated with tap settings, the harmonic results were more insignificant compared to the previous. Therefore, harmonic analysis was not carried out for further analysis. The enhancement of hosting capacity with different mitigation techniques was analyzed while considering voltage violation and power factor violation. The mitigation technique of active network management with balancing loads, tap settings and increasing the loading of the network, increased the hosting capacity from 50kW (31% w.r.t t/f capacity) to 108kW (68%) at no cost. Reactive power compensation schemes did not provide solution as it violates the power factor of the network while mitigating the voltage variation and vice versa. Because, the required reactive power to mitigate the voltage rise becomes significant compared to the active power existence in the network. Mitigation technique of energy storage system also did not provide solution for the low load demand LVDN. The mitigation techniques of network reinforcement methods were applied. It increased the hosting capacity up to 144kW (90%) with upgrading conductor, 153kW (96%) with the installation of OLTC with AVR and the installation of separate PV feeder did not increase the hosting capacity. The cost estimation was done for the mitigation techniques. And it is concluded that the techno economic feasible solution as upgrading conductor with 95sqmm conductor size is selected as the mitigation technique for this existing system. The conclusions of this study are as follow. The network reinforcement mitigation techniques are more suitable than the reactive power compensation schemes, for a PV penetrated LVDN with low active power existence and high feeder resistance, in order to increase the PV penetration, when the voltage rise is due to the feeder resistance. Reactive power compensation methods are suitable for the network with high active power existence and/or high reactive power existence, otherwise it would violate the power factor and/or voltage. Installation of solar PV system in the LVDN will make the system better, to overcome from the effect of the high feeder resistance and it will increase the loading capability of the network while maintaining PQ standards. The increase in the day time loading of the network, increases the PV penetration. Mitigation techniques of active network management of balancing loads and tap settings also increases PV penetration at no cost in such LVDN. Feeder resistance and loading of the network give more impact in deciding the hosting capacity of such LVDN. Therefore, the network reinforcement techniques are more suitable for LVDN with low active power existence and high feeder resistance. Future analysis can be extended for a small scale LVDN with PV systems including significant nonlinear loads and reactive loads.
item: Thesis-Abstract
Development of an electric spring for voltage management in LV network as a consumer level solution
(2023) Hafeel AA; Jayatunga JVUPU; Rathnayaka TD
LV consumers are encouraged to invest on roof top solar and wind turbines to reduce the stress on the utility side. Due to the intermittent nature of these distributed generators the stability of the power system and the power quality has become the major concerns for the utility companies to control. Electric Spring is a modern power quality improvement device which is able to support and regulate voltage events caused mainly due to distributed generators such as wind and solar to the LV feeders without the need of restrictions and control by the modern utility providers. A detailed literature content is presented to give a brief understanding of the applications of electric springs and comparison with other similar devices available at present market. The study was performed in MATLAB/Simulink platform for feasibility of a developed customized electric spring tested for an LV network consumer considering its future load expansions. The study was tested for voltage disturbances such as voltage fluctuations and for voltage sags and swells. A detailed comparative simulation was performed mainly for voltage management in LV consumers for this study. The behaviour of the system was found to be more rewarding with many electric spring arrangements rather having a single electric spring.
item: Thesis-Abstract
Optimum dispatch of turbines in a low head hydropower plant for a given total flow rate and available variable head - A case study for moragahakanda power station in Sri Lanka
(2022) Haputhanthree HGSV; Wijayapala WDAS; Velmanickam L
Hydropower is an extremely valuable resource. There are two types of reservoir based hydropower stations with different main goals. Some are following the demand of the utility and others follow irrigation water requirements. Therefore, always power generation is not at full capacity, and most of the time turbines are at partial loads as well. By optimal hydropower generation and scheduling, great profits can be achieved for the company and also for the country. Therefore, the economical dispatch of hydropower generation provides great opportunities for electric utilities. Moragahakanda hydropower station generates electrical power as an outcome of the irrigation water requirement, decided by the Water Management Secretariat (WMS) which is headed by the Mahaweli Authority of Sri Lanka (MASL). This research presents a strategy for the optimum distribution of dispatched power among its available generating units. The objective is the maximization of the total power generation for a low-head hydropower plant under varying head and for a given total water discharge rate. Hydropower generation scheduling is a nonlinear programming problem. The nonlinearity is due to the generating characteristic of the hydro turbines, whose outputs are generally a nonlinear function of water discharge and net hydraulic head. This research work presents a method that takes into account both the nonlinear characteristic and the head loss effect. This development is done based on the Moragahakanda hydropower station and, MATLAB software has been used for building mathematical models and solving the optimization problem.
item: Thesis-Abstract
Estimation of earth electrode resistance of antenna structures located in non-homogenous geographic terrain using finite element analysis and predictive modelling
(2022) Subasinghe SAVD; Rodrigo AS
iv ABSTRACT The telecommunication sector is consisting of firms that facilitates communication on a mass scale, through the phone or the web, as wired or wireless services. These firms created their infrastructure that permits sending voice, audio, or video and kinds of data or information to be sent anyplace in the world. These companies created their infrastructure that allows transmitting voice, audio, or video and forms of information or data to be sent anywhere in the world. It is observing that the Telecom infrastructure growth is in an aggressive mode even in Sri Lanka due to increase of the user groups and their complex needs for information sharing. As mobile devises become the most attractive device for the customers, operators have to provide these services through higher number of tower structures considering the countries geography and population distribution. With the increasing number of tower constructions and deployment of sensitive equipment with advance features observed due to increasing demand. The tower is a high-elevated structure in the environment. The typical height of the structure may be around sixty meters and may reach up to hundred meters. The towers act as direct grounding path for lightning strike. Providing a sufficient grounding path to such situation is important to mitigate the hazardous nature to the equipment and the livelihood around the structure. A proper earthing system with low earth resistance shall be recommended avoiding possible hazards by ground potential rise. Due to the located small land-plots for tower structures, carefully designed earthing network shall be implemented to achieve a lower earth resistance measurement at the tower. Operators have to maintain the earth resistance at tower sites as per the regulator bench marking. Telecommunications Regulatory Commission Sri Lanka (TRCSL) guideline for antenna structures imposed a recommendation to maintain the resistance level below 5 ohms for classified zones. In order to comply for the guidelines, telecom operators have to deploy optimized earthing networks depending on the tower sites. The tower earthing system consists with copper conductors such as tapes and number of conductive rods to maintain a lower earth resistance value. Estimation of earth resistance is a complicated practice effected by multiple factors due nonhomogeneity of soils. Key observations are the variance in resistivity and resistance readings. At the time of designing, design itself get complex due to parallel conductor formation and its interconnection conductor’s contribution to the results. In order to identify the earth networks effectiveness to surges and lightnings, the site’s earth resistance measurement is the main parameter which we can be measured at a site. This thesis specifically discusses the effects and reasons for directional deviations observed in measured and theatrical values. Site earth resistance measurements have taken along various directions associated with resistive values and assessed with the measurements in four main directions of the sites along the tower legs. Earth networks would be simulated thorough ANSYS Maxwell to achieve earth resistance values. Numerical model will used to represent the resistance value in a single figure. Earthing network profile has been discussed and elaborated in relation calculate the resistance values from the simulation. Validation of the results has been performed through the comparison between simulation results and measurement values. Analysis has done for various soil types in different geographies in different areas of the Mobitel network and possible limitations for study have been discussed. Thesis concludes with a model to represent the accurate earth resistance for the site. Further includes the general assumptions and the possibilities for the further studies of the model proposed in the thesis.
item: Thesis-Abstract
A dynamic load shedding scheme for maintaining system frequency stability with the increasing renewable energy penetration
(20) Herath BHMST; Widanagama Arachchige LN
Renewable energy power plants, especially grid connected solar and wind generation units are displacing the conventional generator stations with rotating machines with inertia. In Sri Lanka, renewable energy generation has begun to increase significantly. The total solar and wind energy penetration is 13% for 2020 and according to the least cost long term generation expansion plan 2018 – 2037 of Ceylon Electricity Board, this amount will be 47% by 2030. With the increased penetration of wind and solar energy generations units having no rotational inertia, there would be a variation in operational and dynamic characteristics in the power system. The power generation of solar power plants varies drastically with the cloud cover. The power output of solar and wind energy varies with their intermittent nature and as a result of it, the system frequency deviations become faster and risking the stability of power system as well. This study is focused on evaluating the frequency stability of Sri Lankan power system at major contingencies during the day-peak periods having maximum wind and solar generation. In Sri Lanka, static under frequency load shedding scheme is used to restore the stability of power system after major disturbances. This load shedding scheme is initiated based on the rate of change of frequency and under frequency settings, which shed pre-determined load amounts at frequency set points in six stages. This thesis analyzes the frequency response of Sri Lankan power system with the maximum wind and solar generation for year 2030 to evaluate the performance of the present load shedding scheme in maintaining system stability. A dynamic load shedding scheme can provide quick and optimal solution by using real-time data of operating conditions. Therefore, this research is proposing a new load shedding scheme based on dynamic load shedding method to improve the frequency stability of Sri Lankan power system while absorbing maximum solar and wind power into the system.
item: Thesis-Abstract
Development of a guideline for designing economical and effective retrofit led street lighting system for Sri Lanka
(2021) Muthuransi LWN; Wickramarachchi NK; Rodrigo WDAS
Nowadays most of the conventional type street lights are been converting to LEDs (Light Emitting Diodes). But there are no proper criteria or standardize methods to replace these conventional type street lamps to LEDs. Only energy saving aspect is garnering more attraction by the governments. But quality aspects like glare, uniformity ratios and color rendering should also be addressed. Otherwise it will not meet the safety and visibility needs of the road users which is the utmost objective of street light designing. The objective of this thesis is develop a guideline for designing economical and effective retrofit LED street lighting system for Sri Lanka. According to EN 13201-2:2015 ‘Road lighting - Part 2: Performance requirements standard, lighting classes were defined by a set of photometric requirements aiming at the visual needs of road users by considering the road categories, number of lanes and street light installation patters in Sri Lanka. Then minimum wattage/ lumen output, ideal light distribution type, luminaire mounting height, overhang and slope angle which should be used when replacing conventional type luminaires were decided for all road categories through a computer simulation process. It was noticed that pay-back period is long due to the cost of LED luminaire and arm modification. Also when we are trying to meet the standard luminance and illumination levels to a road which is having very poor lighting conditions, the cost becomes high. The prices of the LED luminaires are gradually decreasing and therefore lower price levels can be expected in the future and it will reduce these long payback periods. Though these projects have somewhat higher pay-back periods, they are still viable due to energy saving and maintenance cost saving compared to conventional type street lights. Hence when implementing these kinds of public projects investment cost should not be the only reason that should be considered. The safety of road users, upgrade the quality of life by promotion of business activities during the night hours should also be addressed.
item: Thesis-Abstract
Environmental monitoring system for military armouries
(2021) Ranatunge KGJP; Hemapala KTMU
Utilizing explosive material for human activities has taken place since the very day of civilization in several methods/forms. Creating a hazardous harmful environment due to explosive material has become a very big concern since the development of the industrial era. In order to avoid the hazardous environment created by the usage of explosives which leads to effect on human life, the environment as well as the economy of the respective country, it is a must to ensure the proper method of production, transportation, storing and utilizing of explosives be adhered. The development of the explosive chemicals industry has increased exponentially since World War I. Countries around the world maintain explosive storages for many reasons such as military purposes, the fireworks industry, and various other specialized agencies. All chemical explosives have a safe survival period from the date of manufacture and chemical explosives drastically change their chemical properties upon expiration. However, during the past two decades, many accidents/incidents have been reported in explosive storage environments around the world with a greater impact on human life and the eco system. Hence, it is evident that explosive chemical storage management needs more studies and still there is more space for the development of safety measures to avoid such incidents in the future. This research is mainly focused on designing a monitoring mechanism to identify the main changes in the environment of chemical explosive storages by sensing, monitoring and tracking dynamic phenomena in real-time. The proposed monitoring mechanism will detect, identify and alarm when occurring of minor changes of variable factors. The researcher follows the existing chemical explosive storage management safety standards during the study to achieve the research objectives. This research presents an open-source sensor-based design which will check the differences occurring inside military armouries which it uses electronic components likes microcontrollers, sensors and other components comes under IOT (Internet of Things). This design is capable of monitoring quantities like temperature, humidity, availability of harmful gases, inside armouries. Further, this will detect vibration, EMI (Electromagnetic interference) in outside of the armoury. Also, visual monitoring is possible through day and night camera. The collected data and details will be maintained inside a server computer during the testing phase of the design. However, it is proposed to utilize a local server during the actual implementation of the design. The users can access the data by sitting in a control location and also from a remote location through a WAN (Wide Area Network). The aforementioned application will provide essential information to end-user where they can use same for arriving to decision. Further, this will facilitate to make notifications to users when substantial changes occur in the armoury environment. During testing, a cloud-based open-source application is utilized which is easy for monitoring and visualizing of data. The evaluation of proposed designed module has been carried out in several steps. On completion of tests at each & every function in different steps. On the photo type design, it displayed a better accuracy and reliability.
item: Thesis-Full-text
Design a DSM oriented, time of use (TOU) tariff model for domestic consumers with a load research
(2020) Udageachchi EH; Rodrigo A
The night-time peak demand drives the sector investments and hence has become a major target area for Demand Side Management programs aimed at energy conservation and efficiency improvement. Time Of Use (TOU) Tariffs are perceived as a major tool to curb the peak demand. Further, with the growth of the usage of electrical vehicles, there is a tendency of increasing the peak demand because of the charging load. The introduction of the TOU tariff will shift the charging load to off peak hours and the domestic consumers will get the opportunity to charge their vehicles at a cheaper rate. If the charging of electric vehicle at the off-peak hours can be encouraged, the valley in the load profile at the off-peak hours can also be filled while clipping the peak demand. With those intensions, an optional TOU Tariff has been introduced to domestic customers of Sri Lanka in 2015. But the prevailing TOU tariff has not been derived after a load research and it is not attractive to the domestic consumers. The effectiveness of the existing TOU tariff for domestic consumers was analysed in this study. Further an effective TOU tariff for domestic consumers was proposed and the appropriateness of the proposed TOU tariff for the domestic consumers in each block was identified. The benefits of implementing the proposed TOU tariff were also quantified
item: Thesis-Full-text
Study for effective lighting protection system for floating roof tanks in petroleum refinery
(2020) Bamunuarachchi BAT; Lucas JR; Rodrigo A
Refinery is considered as the foremost division of the Ceylon petroleum corporation which ensures the safety of the operation of process plant as well as for maintaining the required country’s demand for petroleum products to enhance the energy sector of the country. Since the un-interruptible continuous refinery operation is critically important to maintain national requirement of petroleum product and protecting the tanks and process equipment is essential. In this study, main concern about floating roof large crude oil storage tank facility. The most general method to prevent the possible damage to floating roof crude oil storage tank is using good earthing. The earthing system provides an electrical path to the ground and performance of the earthing system gets better as the earth loop impedance becomes lower. Since it is among the major concerns currently Refinery engineering staff is struggling with; and a proper method for reducing the sparks due to lightning mainly at critical locations were studied and simulations were done by using the floating roof tank model prepared by using PSCAD software which was validated with the actual model tank tested in the UOM laboratory. Direct and In-direct surge currents were calculated theoretically for 25 kA, 50 kA, 100 kA and 200 kA surges of 10/350 μS & 8/20 μS by applying calculated surge currents to the tank model. Finally, by analyzing all the results and the protection methods of different types of grounding devices were studied and proposed adjustable grounding conductor (AGC) with suitable locations as the optimum solution.
item: Thesis-Full-text
A Methodology for techno-economic comparison of PV inverter structure topologies :
(2020) Kularatne LBSN; Rodrigo A
Sri Lanka’s recent energy policies are focused on promoting economically viable solar power generating schemes introducing novel market segments. It’s envisioned to ensure nation’s energy security while promoting utilization of indigenous energy generating resources. Recent 1 MWp solar power development scheme is one such novel market segment. PV inverters play a significant role in any PV plant performance. Lack of research on identifying the technically and economically most suited PV inverter architecture has caused high risk of failed project objectives. Following research presents a comprehensive framework for a techno-economic comparison of different PV inverter architectures which are central inverters, string inverters, micro inverters and power optimizer systems. 1 MWp capacity PV plant models are designed for analytical purposes of the research. Technical aspects such as energy yield, safety aspects, power output quality, reliability and performance monitoring are assessed using simulation tools (PVSyst, PSCAD and MATLAB), field data analysis, Cost Priority Number method and Markov reliability models. Economic impact is evaluated using Levelized Cost of Electricity calculations and project financial assessments followed by a sensitivity analysis. It’s found that distributed power electronics in PV systems provide higher energy yield, reduced safety risk, higher reliability and lower system down-time due to failures compared to central and string inverters. String inverters and power optimizer systems are more economically feasible in 1 MWp scale. Finally, it’s concluded that the presented methodology furnishes a proper techno-economic comparison for different PV inverter architectures.
item: Thesis-Full-text
Consideration of losses in determining solar PV penetration level in distribution networks
(2020) Nishshanka RMMP; Jayatunga JVUP; De Silva PSN
When it was realized that the conventional energy sources which powered up the industrial revolution are on depletion, a sudden awakening occurred in the field of renewable energy, during the latter part of the last century. As a result, a salient technological development is progressive in the solar PV industry. There are certain benefits including zero emissions, free availability of solar power and economic benefits, turning rooftop solar into an attractive method of investment for domestic electricity consumers. The same global trend has moved towards Sri Lanka during the last five years, due to the government initiative “Surya Bala Sangramaya” on promoting rooftop solar generation. Along with that, loan schemes were introduced to encourage customers to install rooftop solar PV systems. As a result, in urban highly populated areas, distribution transformers are now available with the addition of more than 75% of installed solar rooftop capacities compared to the connected transformer capacity. Rooftop solar PV systems add clean energy to the network, while enabling the customers to get financial benefits from their investment. However, continues addition of distributed renewable generation into the network creates several issues in the system, such as power quality issues, issues associated with reverse power flow etc. Under this situation, now is the high time for utilities to identify the impact to the network with solar PV addition and take remedial action to mitigate the issues immediately. As a preliminary action, introducing maximum solar penetration level is recommended. This research addresses the aforementioned issue and provides a methodology on identifying the maximum allowable solar penetration level, focusing on the power loss. It was observed that the power loss of the network decreases with solar PV addition but after some level, it increases. Though many researches are available for the common issues associated with rooftop solar systems, this is an aspect which has less attention. Thus, it is believed that this research would lay the foundation for certain practical implementations and many novel studies in this discipline. 1-iii In this study, a practical network was modeled and analyzed to identify the behavior of power loss of a distribution transformer with the increment of solar penetration level. Initial case study confirms that power losses increase with high solar penetration level. Therefore, to identify common behavior, generalized model was developed, which could provide platform to define limits for solar penetration. Monte Carlo study was carried out for different cases, and as a result, maximum allowable solar penetration level for a transformer, which can be defined without any conditions was identified. Further, maximum allowable limit which can be defined with conditions also was identified with the applicable constraints. As the ultimate finding of the research, solar PV approval criteria were developed, which can be easily adopted by distribution utilities to add rooftop solar power to the network, in a mutual beneficial mode for both the customer and the utility.
item: Thesis-Full-text
In-rush current mitigation on toroidal transformers with slotted core
(2020) Pathirana MGK; Karunadasa JP
When it comes to transformer industry, toroidal transformers plays a major role, especially in high-tech applications, as they outperform traditional laminated transformers. However, toroidal transformers have a much higher inrush current, especially compared to laminate transformers, which will be a major drawback at the high power applications. Currently there are many options available outside the toroidal transformer to avoid this inrush problem, but reliability issues will still there when using external inrush controlling mechanisms. Traditional inrush current mitigation methods on transformers are not sufficient for toroidal transformers. These methods tend to reduce good performance as well as inrush current. The proposed inrush current mitigation method using a transformer-based slotted core, significantly reduces the inrush current while protecting the excellent performance characteristics which is typical for toroidal transformers. In addition, it offers better control of the inrush current than traditional methods. The proposed method is a slotted core which has a slot in the outer periphery. That controls the saturation inductance and hence the inrush current. At the end, the slotted core maintains high performance without compromising normal operation. This document includes a practical development of slotted cores and as well as experimental tests of inrush current, and finally a new design tool for the optimized deigns.
item: Thesis-Full-text
Feasibility of implementing carbon capture and storage technology in Sri Lankan power sector
(2020) Guruvita KM; Rathnayake TD
Earth is consistently getting hotter with the most noteworthy recorded temperature was at 2016.Gobal warming is the principle explanation behind the temperature increase on the planet. As one of major greenhouse gas, CO2 has a strong influence on global warming. In addition to the global warming, CO2 concentration on the earth atmosphere will directly affect the physiological processes and growth of plants and indirectly for the changes in precipitation patterns and frequency of weather extremes. Nonrenewable energy sources, and fossil fuel based electrical power plants are primary CO2 producers to the environment. Carbon Capture and Storage (CCS) is one of the most forthcoming technologies that captures CO2 emissions produced from fossil fuel power plants. However, this technology is highly resource intensive and therefore it is required to estimate the impacts beforehand. This thesis estimates the feasibility of implementing Carbon Capture and Storage technology in Sri Lankan fossil fuel power plants. In addition to the CO2 emission, other harmful gases, SO2, NOx, and HCl emissions are also considered in this study. Author proposes the most suitable CCS technology for each and every thermal power plant by considering the reduction of CO2 emission and effective resources usage. In addition to that, cost feasibility of implementation of technology is also discussed.
item: Thesis-Full-text
A Cost optimization methodology for design of substation earthing system
(2020) Gunaratne DPCTW; Rodrigo AS
Current practice for earthing grid design for AC substations is mainly guided by IEEE 80 ; 2000 standard. This practice is an iterative process of changing design variables until safety requirments for step and touch voltages and maximum earth grid resistance are met. During this iterative process, the assignment of values for design variables is mainly based on the experience and assumptions of designers. However, this practice is not guided by concerns about cost minimization. Since the earth grid construction occupies a large part of the total cost of AC substation construction, an appropriate cost optimization methodology for the earth grid design for AC substations should be fully identified. The aim of this work is to develop a cost optimization methodology based on a Genetic Algorithm using Microsoft Excell based on IEEE guidelines. This paper analyzes the effect of each earth grid design parameter on the total cost of constructing earth grid and formulation of the optimization problem. This work is also supported by a few sample calculations for a few real-time applications. The calculations show that the developed methodology ensures cost savings of between 30% and 40%.
item: Thesis-Full-text
Criteria for selecting LED luminaires
(2020) Chamari RML; Rodrigo AS
Fluorescent tubes and compact fluorescent lamps (CFL) were the dominant artificial light source for so many years in domestic, commercial and industrial contexts. In the recent years Light Emitting Diodes (LEDs) have gained much popularity with the proven energy and economic benefits and are now used in almost every lighting application. Other benefits include compact size, long service life, ease of maintenance and instant-on quality. Ease of dimming and controlling of LEDs set forth further energy savings. Currently there is an increasing trend for using LED luminaires in many commercial buildings and this has led to form a huge demand for LED luminaires and a huge market competition between the lighting solution suppliers. When the LED bulbs were first introduced to the Sri Lankan market, the retail market was flooded with many low-quality products and most of the domestic consumers could not reap the maximum benefit. Same goes for the LED luminaires. Since these LED luminaires are used in thousands of quantities in commercial buildings hoping to last for decades, if not wisely chosen, huge performance and economic losses have to be endured. With the absence of a national guideline to choose LED fixtures there is an ambiguity among lighting designers and clients when choosing the most suitable luminaire from the wide range of LED luminaires available in Sri Lankan market. Therefore, the intention of this research was to develop general criteria that can be used for choosing the most suitable LED luminaire for a given building. Worldwide building codes and rating systems were studied to identify the minimum performance level expected from the LED luminaires in other countries. LED luminaires in Sri Lankan and foreign markets were technically evaluated. Technical specifications of LED luminaires were obtained from manufacturers’ websites and the market prices were obtained from suppliers. Findings of this research include the evolution of lighting requirements imposed by building codes, performance status of LED luminaires available in Sri Lanka market, general criteria for choosing LED luminaires and justification of the proposed criteria with an example application.
item: Thesis-Full-text
Sri Lankan power system frequency stability with fast growing renewable power addition
(2020) Sandamal YMTA; Rodrigo AS
World is moving forward to a renewable energy base era while retiring conventional thermal energy generation. With this world trend in renewable energy, Sri Lankan power sector has also planned to integrate more renewable energy into the Sri Lankan power system within recent years. This research analyzes the effect of renewable energy integration in small island mode power systems like Sri Lanka with actual measured data. Impact of the intermittent nature of the renewable power and the replacement of conventional power plants with non-inertia supportive renewable plants are mainly focused in this research work. This research demonstrates renewable power variations in Sri Lanka and subsequent power system stability with these variations. Simulation results indicate that power system is not stable with high share of renewable power integration. Combined operation of selected conventional power plants and renewable power plants has been proposed to stabilize the power system. Technological improvements of the renewable plants to mitigate adverse effects were also addressed during simulations.
item: Thesis-Full-text
A Power supply reliability assessment model for the Colombo suburban railway network
(2020) Munasinghe DT; Perera R; Siyambalapitiya T
An electrified railway network is one of the solutions for Colombo traffic congestion due to high population density and high daily passenger flow into the city from the suburbs. Although the initial cost of a railway electrification project is higher compared with other alternatives such as improvements to bus transport, energy, maintenance and operational costs can be lower if the system is designed, maintained effectively and used efficiently. System failures or, delays in system operations should be minimized to reduce the time wasted in traveling. Reliability and punctuality are the major factors to attract more passengers to use public electrified transport facilities for their daily travel. Power supply is a critical factor to maintain a higher reliability in an electrified railway system. Designs to upgrade the 230 km long Colombo suburban railway network commenced in 2017 and currently in progress in four stages. Different options for the power supply configuration and the back-up power systems have been identified, qualitatively evaluated and then recommended for implementation. A quantified reliability assessment has not been reported in the design. A standardized procedure and a reliability assessment model would be required to evaluate the reliability of each optional configuration to supply power and backup power. In this research, optional configurations to supply power to the future electrified railway system of the Colombo Suburban Railway Project area were developed. Reliability assessment was conducted for each optional configuration using the models developed and simulated using Monte Carlo simulation technique. Reliability worth analysis was done to weigh the costs and benefits of configurations with higher reliability. The model developed can be used for reliability assessment of the power supply to any suburban electrified railway system in Sri Lanka.
item: Thesis-Full-text
Optimum hybrid power supply system via battery bank mixing for telecom base stations
Wijetunga, WWBS; Rodrigo, AS
The power requirement to operate a radio base station site is getting increased day by day due to the introduction of new services. Apart from that in order to provide a high-quality service to their customers operators tends to invest more on redundant power sources as well. At the same time, it’s very important to reduce the capital costs and operational costs as much as possible to maintain the financial stability of the mobile operating companies. So, it’s important to address the power requirements in an optimum manner. This thesis comprehensively explains an effort taken to identify the optimum way of providing grid power and the backup power for the telecom base stations. A simulation model is developed to derive the optimum hybrid power supply model with the best combination of mixed battery bank and diesel generator that determines, the optimal capital & operational cost for an RBS site with given load, type and environmental factors. This simulation model will mainly address existing energy sources optimization, backup power for poor grid connected sites and capacity upgrades in backup power supply. Also for the first time in Sri Lanka battery bank mixing was introduced for the radio base station sites with the help of this study.
item: Thesis-Full-text
Development of a generalized methodology for blackout restoration : a case study of Sri Lankan power system
Sirisena, KLU; Prasad, WD; Fernando, R
Blackouts are been reported throughout the history worldwide and nowadays, a moment without electricity causes a greater loss of lives and economy. On the other hand, restoration of a blacked-out power system requires expertise of experienced engineers which is not completely reliable under certain system complexities. Generally, it turns out to be a trial and error approach under the guidance of experts. This paper proposes a generalized aiding methodology for solving the restoration problem by assessing the next system state for a given decisions of the system operator. With adequate system information (pre-outage data, equipment availability etc.), this proposed decision support methodology could mitigate unexpected cascaded tripping events which occur owing to lack of confidence in next state during restoration. The case study considers restoring of a crucial subsystem of Sri Lankan power system, Colombo – Kelanitissa system along with Laxapana System. Successful attempts shall fulfil load flow while maintaining system parameters and stability during switching operations. The results compare and depict the success in solving the restoration problem with proposed real-time, offline methodology against trial and error approach. Further it suggests the requirement of parallel computer based simulations on restoration of other sub systems and synchronizing events during actual implementation.
item: Thesis-Full-text
Power management algorithm for stand - alone hybrid energy system
Lakmali, KG; Rodrigo, WDAS
In Sri Lanka grid-based electrification is possible up to maximum 95% ofthe population and balance 5% ofthe electrification has to be mainly depending on off-grid technologies such as solar PV, wind, biomass and micro hydro [2].Mostly these off grid Hybrid Energy systems are used to provide electricity in rural areas which are located far away from the grid connection. In this research, general power management algorithm has built up for standalone hybrid energy system. It controls the sharing of generated power and optimizes the hybrid operation, maximizes the use of energy produced by renewable sources and minimizes the cost ofthe energy produced by the system. The simulation model ofstand-alone system is developed from mathematical models of solar photovoltaic system, wind turbines, battery and diesel generators. The model of solar photovoltaic energy conversion system is constructed with maximum power point tracking control to extract maximum power from the solar photovoltaic system. In order to validate the proposed strategy under real situations, optimized hybrid energy system was designed for Delft Island by considering the future demand. The effect of the capital cost, operation & maintenance cost, life time of the components, load pattern, available renewable resources level has been considered in the optimization. “HOMER” optimization tool was selected for optimization and optimized capacities of each component considered for power management strategy simulation in “MATLAB” simulation tool. The developed firmware permits to determination of diesel consumption and Load Loss probability of different kind of energy systems. Results obtained from the simulation are presented to validate the control algorithms developed in this work and in order to examine the economic viability of the proposed system, the total net present cost has been calculated for 20 years ofsystemic lifetime.