Browsing by Author "Wijayapala, WDAS"

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item: Thesis-Full-text
A Conceptual design for a tower type concentrating solar power plant near Hambantota
Wijayawardhana, NABR; Wijayapala, WDAS; Fernando, DGR
In this study the basics of a central receiver type solar thermal power plant including a thermal storage are studied. Further, the technical feasibility of a central receiver type solar thermal power plant near Hambantota is investigated. The requirement of a power plant and the size of the plant are determined. The availability of solar resources in the area and the best area to locate a solar thermal power plant is also studied. The other required resources such as water, lands, proximity to transmission lines are taken into consideration. Further the impact on the environment and the possible measures to mitigate such impacts are examined. In addition, the technical features of a central receiver type power plant are studied and a conceptual design for such a power plant has been developed. In the conceptual design, the total required number of heliostats or reflectors, the heliostat field layout, the receiver size, the thermal storage size and the tower height have been determined. Finally, the economic feasibility of the plant is checked considering the available soft loan facilities which can be obtained from international development banks such as Global Environmental Facility (GEF), World Bank and Japan International Cooperation Agency (JICA). The economic benefits from the Carbon credit program have also been taken into account. Finally, it is concluded that certain cost reductions and economic conditions are required for the project to be viable
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Analysis of non technical losses in distribution networks, mitigation methods and costs
(2015-07-06) Ramasinghe, NR; Wijayapala, WDAS
Ceylon Electricity Board (CEB) is engaged in generation, transmission and distribution of electrical energy in Sri Lanka with support from Lanka Electricity Company Ltd (LECO) for distribution in certain areas and generation support from a number of private power plants. CEB is incurring huge commercial losses annually supplying electricity to 94% of households at a unit price lower than the actual unit cost. Minimizing losses in generation, transmission and distribution is of vital importance to any utility. Out of these losses, the distribution loss happens to be the larger component. Distribution system loss can be subdivided as Technical Loss (TL) and Non Technical Loss (NTL). The investment requirement for reducing TL is higher compared to the investment required of reducing NTL in distribution networks. This has drawn special attention for the NTL reduction programs in CEB. For devising and implementing suitable preventative and corrective actions of reducing NTL, it needs to be identified accurately. But identifying NTL is more difficult because no properly recorded information is available in many divisions in the CEB. The aim of this research is to study NTL in the distribution network to find mitigation measures through new technology and new systems. Causes of NTL are identified and quantified to the best possible accuracy and their impacts on NTL are discussed. Further, benefits of applying new technologies such as Aerial Bundled Conductors (ABC) and smart meters for mitigating NTL with cost benefit analysis is also included in this study. Legal framework of Sri Lanka was examined towards implementation the NTL reduction measures and some suggestions are made for future amendments to the Sri Lanka Electricity Act of 2009. In summary, out of the 11.24% system losses in 2012, 0.64% is generation loss, 2.02% is transmission loss and 8.59% is identified as distribution loss. This study indicates that on average the 10.06% of distribution loss of energy input to Distribution Division 4 in 2012 contains 3.92% of NTL component; further details of the composition of the NTL are discussed in this thesis.
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Analysis on wind solar hybrid system for stand-alone power generation in Sri Lanka
Karunasekara, HPHK; Udawatte, L; Wijayapala, WDAS
The 100W wind home power generation system fabricated and installed by the NERDC at Nikavatiya in Kurunagala district is facing insufficient power generation within few months due to monsoon wind changes. The researcher was motivated to develop a hybrid wind solar power generation system to overcome this challenge. The power consumption of a rural house was evaluated and metrological data (wind speed and solar irradiance) were measured during year 2008 as part ofthis study. According to the metrological data, 3.92 m/s wind speed and 5.44 kWh/m2/day solar potential could be obtained from the site annually. The dynamic behavior and simulation results in a stand - alone hybrid power generation system of wind turbine, solar array and battery storage are presented by this analysis. This study is to review the state of the simulation, optimization and control technologies for the stand-alone hybrid solar-wind energy systems with battery storage. The hybrid system includes a 100W wind turbine, 150W solar array, 70Ah Lead -acid battery, AC/DC rectifier and DC/AC inverter. The NACA 4415 two bladed wind rotor performance was analyzed theoretically by using blade elementary and momentum theory and the parameters ofthis analysis were found by using C++ program. The performance of a Fuzzy Logic Maximum Power Point Tracker (MPPT) controller (hill climbed) was applied for variable - speed, fixed -pitch NERDC small-scale wind turbines as wind speed sensor less application. More 35 % of extra energy absorb from the system by using Fuzzy Logic controller than fixed voltage method. The maximum power point tracking (MPPT) method based on perturbation & Observation (P&O) searching algorithm was applied to stand - alone solar photovoltaic system. The P&O algorithm was tested with actual irradiance data provided by simulations, using sunny day and cloudy day two sets of irradiation data. The simulation result shows the efficiency of 96.2% for P & O algorithm. The 70Ah lead - acid batteries were used in for the analysis and the same type is used for the hybrid solar-wind power generation system. Lead - Acid battery model was developed and simulated with Simulink software platform. Also laboratory testing was done according to the SLS 1126 test procedures. MATLAB TM Simulink simulate individual wind and PV dynamic models of hybrid system. HOMER has being used extensively to optimize the hybrid system size, sensitivity analysis with case study data in stand-alone areas in Sri Lanka. The 60 W solar PV array and NERDC 100W wind turbine with 70Ah four battery bank is proposed as hybrid power system and battery state of charge (SOC) is close to 100 % present level annually. Correct modeling of the dynamic and non linear systems is an important area ofthe study, but various difficulties remain in the current study. Some approaches of analysis are limited with use of commonly available simulation software. Physical implementation of the system with power electronics remains for future research. The author suggests that solar home power system is suitable below the wind speed of 3.5 m/s , solar and wind hybrid system for the wind speed between 3.5m/s to 4.5 m/s and the wind turbine home power generation system for the wind speed above of 4.5 m/s to fulfill the rural energy requirement.
item: Thesis-Abstract
Assesment of factors affecting solar irradiance and development of a model for predictions
(2015-07-06) Kushal, DHK; Wijayapala, WDAS
In Sri Lanka Ceylon Electricity Board plays the role of the system controller by dispatching the energy generated from different power plants to meet the energy demand. Power generation from renewable energy sources such as wind, mini-hydro, solar etc is becoming increasingly popular due to environmental concerns. With the introduction of the net metering system a large number of rooftop solar power systems are getting connected to the national grid. However, it is not possible to predict the energy generation of solar power plants in advance. Therefore, the system controller has no information about the tomorrow’s possible energy availability from these non-dispatchable power plants. Then the only option left with the system controller is to reserve the costly thermal power plants in order to meet the future energy demand. The outcome of this research enables the system controller to predict the possible energy generation from solar power plants based on the weather forecasts. This will provide the system controller with predictions on energy generation and capacity of solar power plants connected to the grid. These predictions will enable to prepare the dispatch schedules accordingly. In this study, the effect of the geographical and meteorological parameters for predicting daily global solar radiation in Sooriyawewa, Hambantota is investigated. A multiple linear regression was applied to explain the relationship among solar radiation and identified geographical and meteorological parameters such as cloud cover, sunshine duration, precipitation, open air temperature, relative humidity, wind speed, gust speed, and sine of declination angle. Variables in these equations were used to estimate the global solar radiation. Values calculated from models were compared with the actual measurements to validate the model. The application of the model to other geographical locations should be carried out as a further study when sufficient data is available for such locations.
item: Thesis-Full-text
Assessment of the impacts of electricity subsidies in Sri Lanka
(2015-10-29) Kankanamge, TN; Wijayapala, WDAS
Government of Sri Lanka provides subsidy on electricity to uplift the living condition of citizens for decades. This research project mainly scrutinize, whether the objectives of the electricity subsidies have been fulfilled or not. Further, both positive and negative impacts of electricity subsidy is descriptively discussed. Appropriate remedial actions are proposed for the betterment of identified indirect negative impacts. In the analysis, it was found that some primary objectives of the electricity subsidy have not been achieved. One of the most subtle negative impact recognised is the encouragement of energy inefficient equipment usage among subsidized consumers. A case study was conducted in Ratnapura District to investigate the energy inefficient equipment usage and to quantify the electricity wastage. Findings were used to estimate the electricity wastage in whole country due to inefficient equipment. Further, it was found that the existing tariff structure encourages the energy inefficient equipment usage and it acts contradictory to the fundamentals. As a possible way of saving electricity and catering the demand at night peak, replacement of incandescent lamps were analyzed and possible saving were estimated. Moreover the investment on replacing incandescent lamps by energy efficient equipment was estimated and financially evaluated with the returns. Additionally, it was found that the eligibility criteria of current subsidy is having many loopholes. The major shortcoming is that it allows unwanted people to enjoy the subsidy. The additional burden to the treasury has been estimated as LKR 11 billion per year. It was seen that modifications are needed for electricity subsidy eligibility to ensure only needy people receive the electricity subsidy. Meanwhile modifications are needed for tariff rates fixing method. New equation shall be introduced based on actual generation cost for the tariff rates calculation with appropriate justifications. Further it is recommended to reduce the electricity subsidy gradually to zero. Discouragement of energy inefficient equipment usage by introducing new taxes, promoting energy efficient equipment, introducing subsidies to energy efficient equipment and conducting awareness programs regarding the electricity conservation are the other recommendations to minimize the negative impacts of electricity subsidy.
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Clearance to buildings from overhead transmission lines
Kodithuwakku, KS; Lucas, JR; Wijayapala, WDAS
Withthe increasing demand for electricity supply and the country development, Searching of Transmission Line corridor across populated areas is a major difficulty faced by the utility company. Further, most of the funding agents are very much concerned bout the environmental impacts due to the constructions. The width of Transmission Line corridor is proposed for two different Transmission Voltagesand the sharing of single corridor for more lines and the required widths are proposed. Possibility of building construction and planting of trees within the Transmission Line corridor is decided and the maximum heights for constructions are also proposed.
item: Thesis-Full-text
Design of Colombo city electricity network for anticipated future demand
Rajapakshe, DGKMTN; Wijayapala, WDAS; Wijekoon, H.M
In “Colombo City Development Plan – 2020” published by Urban Development Authority in 2008, Colombo City is divided into 9 zones based on the major developments in each zone. The major projects proposed to be completed by 2020 are sited in concentrated development zone and port related activity zone. With the upcoming projects in each zone, the amount of electricity required in each zone will be increased and existing load centers will be shifted. Specially commercial and industrial zones will require higher amount of energy. With the zoning plan & upcoming projects most of the grid substations with two numbers of transformers & underground cables will be fully overloaded during peak hours in future. Therefore tripping of one transformer and/or underground cable will cause power interruptions to large number of industrial and domestic customers since rest of the network can’t cater the demand. This is due to the capacity limitation of the present transformers, limitation of the number of transformers in each GSS, capacity limitations of underground cables and not having GSSs in required load centers. These are major setbacks in Colombo City system operation and reliability. Presently Colombo city distribution network is operating at 11 kV voltage level. Due to this voltage level, with the future growing demand network loss will also grow drastically. In addition to the line losses, present transformer impedances also contribute to these losses. This dissertation discusses on designing of an upgraded network for Colombo City in 2021 with minimum overloading of transformers and underground cables. Further, analysis is done to examine the best transmission voltage in 2021 according to the demand growth. Load forecast was prepared up to 2021 based on past data obtained from system control center of Ceylon Electricity Board and spot load data obtained from UDA. Accordingly, the load centers are identified. Sri Lankan power system has been modeled using the PSS®E (Power System Simulator for Engineers) software. The Existing Colombo City Electricity Network was simulated using this model and its drawbacks were identified. Two effective networks i.e. 132 kV solution and 220 kV solution, were proposed for Colombo City in 2021and system improvements were tested with simulations. The observations and results obtained from the simulations include short circuit levels and transmission losses. Economic and financial analysis was carried out and finally comparing all the results the most effective network for Colombo City in 2021 was selected. This newly proposed network for Colombo City in 2021 will improve the Power System reliability and have a definite positive effect on customers which in turn improve the welfare of the people and economy of the country.
item: Thesis-Full-text
Determination of capitalization values for no load losses and load losses of distribution transformers
(2015-10-29) Bandara, HMSLG; Wijayapala, WDAS; Gamage, SRK
Transformers are one of the better efficient components in the electricity distribution network. Basically substation transformers and distribution transformers are currently used in the electricity distribution network in Sri Lanka. Evaluation on the purchasing price of the transformer is not enough during the purchasing process. There are losses due to no load losses and load losses in the transformer during life which is about 30-35 years. Therefore, transformer purchaser must be look at total life time cost of the transformer during the purchasing process. Traditionally, this evaluation is done based on Total Owning Cost (TOC). Currently in Sri Lanka, CEB does not use competitive bidding process in purchasing of distribution transformers. And also, CEB has not defined capitalization values for distribution transformers to evaluate them based on TOC. Main objective of this research is to set up a methodology to calculate capitalization values for distribution transforms in Sri Lanka using IEEE loss evaluation guide. Capitalization values for distribution transformers depend on capacity cost and energy cost, economic considerations and load profile of distribution transformers. In this research, capitalization values are calculated for three different load profiles, i.e. rural, semi urban and urban. A computer based methodology was developed to calculate capitalization values as an outcome of this research. In future, CEB can purchase distribution transformers by using these capitalization values for different applications, i.e. rural electrification, loss reduction in urban cities, augmentation of distribution transformers, etc. And also, any other utility can use computer based model to calculate capitalization values for distribution transformers at any given time corresponding to a set of economic and other parameters.
item: Conference-Extended-Abstract
Determination of one dimensional earth resistivity profile in multilayer soil
(2007) Dharmadasa, IT; Lucas, JR; Udawatta, L; Wijayapala, WDAS
Main intention of Geophysical resistrvity surveying is to interpret the subsurface conditions for engineering applications. The earth exhibits a far from uniform structure and therefore the surface resistivity varies from location to location as well as on seasonal basis. Often, the structure will have resistivity layers related to the physical layers such as topsoil, sub-soil, and bedrock. Clearly these layers or divisions in soil structure will have a considerable impact on both soil resistivity and earth resistance/impedance. This anisotropy found in platy structures will result in an apparent resistivity which with wide variations.
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Developing a mathematical model to predict the daily demand for electricity, based on weather parameters
Jayasekara, IN; Wijayapala, WDAS
System Control Centre (SCC) of Ceylon Electricity Board (CEB) conducts short term (hour ahead, day ahead) and medium term (up to three years ahead) demand forecasting based on historic demand, seasonal patterns, time of day and regional sales forecast. However, there are no measures taken as yet to include the influence of weather conditions such as temperature, humidity, sky cover, wind speed, etc. in this forecasting exercise. Ambient temperature and humidity has become dominant parameters for electricity demand with the introduction of space cooling methods in recent history. The study focuses not only the influence of temperature and humidity to electricity demand of Sri Lanka but also the influence of wind speed and wind direction. Study focused to build up a linear model using hourly historical demand data and meteorological data of four consecutive years using IBM SPSS statistics V 21 software. Meteorological parameters were taken as the independent parameters and hourly demand data was taken as the dependent parameter. Correction factor was needed to include the effect of yearly demand growth, for a better correlation. Every demand data point was corrected based on the average demand growth (yearly) and time of day. Weekdays were taken as one set and Saturday and Sunday were taken separately. Model consists of 72 independent equations (24 representing a weekday, 24 for Saturday and 24 for Sunday). Correction factors were calculated for calendar holidays which have major influence on electricity demand. Model validation was done for historical weather data as well as forecasted weather data. Predicting average absolute error was under 9% decreasing more with the prediction date close to the real date. Model is recommended to be used for short term demand forecasting and power plant dispatching in Sri Lanka.
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Development of a neuro-fuzzy system for condition monitoring of power transformers
Sellahannadi, JR; Wijayapala, WDAS; Udawatta, L; Shanthi, KPK
Well-being of Power Transformers is crucial to the reliable operation of a Power System. They represent a high capital investment in a Transmission Substation while being a key element determining the loading capability of the station within the network. With appropriate maintenance, including insulation reconditioning at the appropriate time, the technical life of a transformer can be extended. Assessment of Power Transformer condition is very important to maintenance engineers on the way to diagnose incipient faults and implementation of necessary maintenance plans to prolong their life span. Therefore different testing methods and diagnosis techniques are used for condition assessment of transformers; namely Dissolved Gas Analysis (DGA), moisture content measuring tests in oil/paper, Insulation Resistance (IR) measurement, acidity in oil etc. Accuracy of the final conclusion depends on the experience and knowledge of the maintenance engineer and the data which he referred to. Therefore, it is appropriate to have an Expert System, as a guide to maintenance engineers in the Ceylon Electricity Board (CEB), so as to address the above problems. This thesis describes the degradation of insulation, ageing process, faults and testing methods of transformers. Much attention was paid to DGA as a diagnosis tool. This thesis introduces two computer based expert systems to analyze the results from various diagnosis techniques and tests which are used in CEB at present. First program was written on Visual Basic environment and included essential tests including DGA which are carried out by CEB for its transformers. Knowledge base for this program was developed by using various standards, text books, transformer manufacturers' recommendations and the opinions of my supervisors and experienced engineers. Twenty Five (25) numbers of DGA test results of transformers were analyzed by using this program and such transformers were grouped according to the IEEE standards. Limitations of conventional DGA methods with frequent non decisions can be addressed by fuzzy-logic based diagnosis for power transformer incipient faults. Therefore, the second program was developed to meet the above demand by using Adaptive Neuro-Fuzzy Inference System (ANFIS) in MATLAB Environment. The developed ANFIS-based diagnosis system provides further improvement to fuzzy-logic based techniques by providing auto-learning capabilities. This program was tested for faults with 30 DGA test results and the outcome is within the satisfactory level.
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Distribution transformer model for transient studies
(2015-02-22) Hasthanayake, LS; Lucas, JR; Wijayapala, WDAS
Distribution transformers are expensive components in the distribution network of the country. Records from Ceylon Electricity Board show that considerable numbers of failures of these distribution transformers are due to lightning surges. This is a huge cost for the utility suppliers like Ceylon Electricity Board (CEB) and Lanka Electricity Company (LECO). The study area of distribution transformers under transient conditions needs to be broadened and availability of a transformer model to represent a distribution transformer used in Sri Lankan network is very much essential. If there exists a model with acceptable level of accuracy to represent the distribution transformer under transient conditions, many criteria relating to the distribution lines can be studied without actually implementing them. In this research, a methodology is presented to obtain a model to represent a distribution transformer under transient condition. Parameters are calculated and a model is presented based on the details of the 160 kVA, 33/0.415 kV, distribution transformer. The same methodology can be extended to obtain the respective models of distribution transformers with other power ratings. The proposed model is simulated using the PSCAD software and output results are obtained when the standard lightning waveform and chopped surge waveforms are input to the model. The simulated output along the transformer winding is observed and compared with the result of an already carried out experiment presented in a research paper. Both the simulated and experimental outputs took fairly the same shape and the model is validated. Key words: Transformer Model, Surge Distribution, Winding, Simulations
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The Economic comparison of reservoir type and run of the river type hydropower plants: a case study for upper Kotmale
Amanda, HAH; Wijayapala, WDAS; Lucas, JR; Fernando, WJLS
At present, greenhouse gas emissions are considered as a factor even for hydropower because of the identified gas emission possibilities. Thus when planning a large hydropower project at a selected location, it is important to take the decision on which type of power plant to construct (such as a reservoir type or run of the river type) based on an economic comparison including environmental considerations. Out of the implemented two large run of the river type hydropower projects in Sri Lanka, Upper Kotmale was selected as the case study for this research. The existing Talawakele run of the river project and an earlier suggested Caledonia reservoir project were selected for the comparison as competitive projects. Net greenhouse gas emissions from the both projects were estimated in this study. For the economic comparison, the levelized cost of electricity of both projects were calculated considering related costs, benefits under Clean Development Mechanism, and annual electricity generation. The results show that the unit cost of electricity generation from run of the river type project is substantially lower than that of reservoir type project. As Upper Kotmale is a peak serving plant in Sri Lanka, a separate comparison between the two projects was done considering their night peak operation. The results show a loss to the country by energy reduction due to not using the potential for reservoir type. Based on the results of the case study, it is concluded that for future large hydropower developments, a detailed study, including Clean Development Mechanism benefits, to be carried out case by case before taking the decision on reservoir construction. The research outcome will not only be important to any remaining hydropower potential development in Sri Lanka but also to other hydropower dominant countries in the world.
item: Thesis-Abstract
Economic loss optimization technique for distribution transformer sizing
(2014-07-31) Thushara, RMHL; De silva, N; Wijayapala, WDAS
The Distribution system is a dynamic system which requires frequent system augmentation to ensure customer satisfaction and optimum system operation. Planning of such a system needs to consider many variables and alternative solutions in a complex process to select the system components at their economical size combination. Since distribution transformer is the major cost contributor in the secondary distribution network, correct sizing should be achieved via economical optimization in avoiding under utilization. Adoption of a global design methodology is preferred in this case. This research was intended to implement a model based secondary distribution planning strategy which will be capable enough to provide final solution in a minimum time with economic evaluation. The application of geometry to represent distribution transformer service area is helpful in the system analysis and it simplifies greatly the complexity of the system while allowing comparison of alternative arrangements in a faster manner. Several options are analyzed during this study in comparing actual system data of large number of distribution transformers in Lanka Electricity Company's (LECO) l lk V/400V system. It is concluded that the model of hexagonal geometric service cell area with trapezoidal separation per feeder is the best fit model to represent a secondary distribution transformer service area. This selection is based on voltage oriented. This includes three main feeders originating from the distribution transformer located at the center of the hexagon. Set of application charts for commonly available distribution transformers are developed in the research. This gives faster method of investigation about voltage drop and power loss for a particular distribution transformer in various configurations. The computer program is finally implemented in MATLAB to generate final solution for the optimum transformer capacity. Existing network expansion or reinforcement is investigated in this program. Economic optimization is implemented in both cases where Genetic Algorithm is used as an optimizing technique for the first option which achieves converged to the global optimum point in a few seconds. A detail case study is done with actual system data to verify the final results.
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Efficiency improvements to the hydro power plants in the Laxapana complex
(2015-07-06) Jayawardene, CDRJ; Wijayapala, WDAS
The main objective of this research is to present effective efficiency improvements to the hydropower plants in the Laxapana Complex. At present, electricity consumption in Sri Lanka is being increased at a rate of about seven present. Hence, improving the efficiency in an existing hydropower complex will lead to an increase in the electricity generation capacity of the National Grid using the same waters of the existing schemes. In this research, observed key areas are techno-economically analyzed with the view of efficiency improvement. All the areas introduced are important when they are viewed as total energy improvement projects. However, In order to implement a project, it should be viable. Hence, in this report, certain areas are discussed, and only viable modifications are presented as efficiency improvement projects. In this study, efficiency improvement to the Old Laxapana power station through a new generator design, capacity improvement to the Laxapana pond in order to minimize annual water spilling, new generator installation to the Samanala Power Station and leakage analysis of the New Laxapana tunnel have been proposed. For the analysis, past data and the findings of certain researches have been used. The study of the Old Laxapana Power Station was carried out focusing on the Old Laxapana Stage-II generators. From the cost-benefit analysis, a simple payback period of four years was observed. Next, from the cost-benefit analysis of the capacity improvement of the Laxapana pond, a payback period of 14.3 years found, and it was accepted considering the lifetime of the dam proposed. After that, a seven-year simple payback period was observed by proposing a 13.6 MW-generator for the Samanala Power Station as capacity improvement. Finally, the tunnel leakage analysis for the New Laxapana power station was carried out, obtaining 6.5-year simple payback period, and, hence, it was recommended to implement the repair during the rehabilitation.
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Engineering productivity of Sri Lankan engineers
Wijayapala, WDAS; Perera, R
The oxford dictionary defines engineering as ··the branch of science and technology concerned with the design, building, and use of engines, machines and structures". The word ''engine" has evolved to engineering in early days, which now covers a vast area of applied sciences from nuclear to food engineering and involves many engineering techniques and engineering processes. Engineers apply the theories and principles of science and mathematics • to research and develop economical solutions to technical problems. Their work is the link between scientific discoveries and commercial applications. Engineers design products, machinery to build those products, factories in which those products are made, and the systems that ensure the quality of the product and efficiency of the workforce and manufacturing process. Engineers design , plan, and supervise the construction of buildings, highways, and transit systems. They develop and implement improved ways to extract, process, and use raw materials, such as petroleum and natural gas. They develop new materials that both improve the performance of products and help implement advances in technology. They harness the power of the sun, the Earth, atoms, and electricity for use in supplying the Nation's power needs, and create millions of products using power. Engineering knowledge is applied to improving many things, including the quality of health care, the safety of food products, and the efficient operation of financial systems. 1 Engineers not only develop themselves but als9 train other technical personnel working in various fields and capacities. They guide them, instruct them and teach them how engineering principles are adapted in the best practical ways . Engineers consider many factors when developing a new product. For example. in developing an industrial computer, engineers determine precisely ''hat function the computer needs to perform; design and test its components; fit the components together in an integrated plan; and evaluate the design ' s overall effectiveness, cost, reliability, safety and marketability. This process applies to many different products, such as automobiles, chemicals, turbines, and even toys.
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Evaluation of the economic benefits of shifting air conditioning loads from evening and day peaks to off peak hours
Lalitha, TGR; Wijayapala, WDAS; Dalugoda, CN
With the development of industries and changes in living standards of the society, demand for electricity is rapidly increasing in every year. In order to maintain the demand supply balance and to provide uninterrupted supply, utility has to supply the electricity demand in the most economical way. Building new power plants is not always the most economical solution. The trend now, is towards reducing and controlling the demand through Demand Side Management (DSM) techniques which is almost always an economical and environment-friendly solution. In this thesis, Heating, Ventilation and Air Conditioning (HVAC) system of Cinnamon Lakeside Hotel is analyzed to identify the potential DSM options that can be implemented. Thermal Energy Storage (TES) was selected as the DSM option to store cooling load in off-peak hours of the day and use it in peak and day hours of the day. Technical viability and potential saving that can be achieved through TES in hotel sector of Sri Lanka is further analyzed. Benefits of Thermal Energy Storage systems to the industry and to the utility is separately analyzed in this study. The conclusion of the thesis is that Thermal Energy Storage technology is a viable DSM method for the hotel industry in Sri Lanka. It is the responsibility of the Government and the Utility to promote DSM methods to its customers and motivate them to invest.
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Feed water heater for increasing boiler efficiency : case study at pelawatte suger industry
Samankumara, JM; Wijayapala, WDAS
Sugar cane is grown in rural areas in Sri Lanka, and the residue of sugar cane production called bagasse, can be a cheap source of primary boiler fuel, when processing sugar cane. For each 100 tones of sugar cane harvested and milled, 9-10 tones of sugar is produced together with 29-33 tones of solid waste in the form of crushed cane, or bagasse. Typically, the mill uses about 53% of bagasse in a low efficiency steam cycle to produce the electricity and steam which needs for own use. Surplus bagasse is sometimes used for paper making or cattle feed but in Sri Lanka neither of these applications are effectively used. Bagasse is a major bio-mass fuel, which can be used to produce significant quantity of surplus electricity. Progressive sugar cane companies are beginning to see the advantages of creating a substantial additional cash flow by setting up cogeneration power plants fuelled by bagasse. Using proven technology a 5000 tones/day cane mill can use its own bagasse to supply the mill with steam and power and export approximately 22 MW of electricity. Some large sugar cane mills currently have co-generation power plants that export over 25 MW. In Pelwatte sugar industry, there is 3MW electricity generation and 90T/h steam generation to meet its total demand. Modern conversion systems also ensure lower air emissions meeting latest environmental standards. Because of the harvesting of sugar cane is seasonal, maximum utilization of the co-generation plants is only achieved, if bagasse is stored for use in the off season or other biomass or fossil fuels are employed. Therefore, optimum usage of bagasse is important for minimizing fossil fuel usage. In Sri Lanka, price of fossil fuel is increasing rapidly. If the sugar factory consumes fossil fuels, then those factories are directly affected by the price changes of fossil fuels. For the existence of Sri Lankan sugar industry, and to compete with other sugar industries all over the world, optimum usage of bio-mass usage, such as bagasse is very important. For the optimum usage of bagasse consumption, various methods can be used. But the sugar factories, which are already installed, have been equipped with some of these methods. Later modification for optimization and saving of bagasse directly affects the whole system. To optimize bagasse usage, and to minimize fossil fuel usage, it was decided to increase existing boiler efficiency by introducing a feed water heater. But for that, extensive studies were conducted. By this modification it was revealed that an increase of 3% in boiler efficiency could be achieved thereby a saving of 54.2 million LKR could be gained annually. In addition, an obvious reduction of fossil fuel usage and reduction of emissions are the other achievements. Outcomes of this project are significant and it is bound to benefit sugar industry in Sri Lanka.
item: Thesis-Abstract
Good workman practices for power distribution line connections
(2014-08-01) Jayasekara, AGDP; Lucas, JR; Wijayapala, WDAS
Defective electrical connections in power distribution systems will result many circuit and equipment failures. Power distribution loss reduction and power system reliability improvement are becoming very important vicinities to be investigated. There are several methods available for power distribution loss reduction. Energy losses by connectors installed in power distribution network is one of the highly concerned. Quality of power line connections directly affects the power system reliability. Compression connectors or compression joints are a popular type of connectors used for joining or terminating conductors in power distribution network. Identification of good workman practices for power distribution line connections is important to make the power system more reliable. Standardization of process of power line connector installation and proper die selection technique for compression connectors is essential for power system reliability improvements. This study is an attempt to identify good workman practices required for making perfect power distribution line connections. This will be a guide in the assembly and preventive maintenance of efficient electrical connections for power distribution circuits. An efficient connection shows minimum resistance, both at initial assembly and in the long run. Data and experience gained through usage on power line connectors by Ceylon Electricity Board (CEB) is the basis of this study. The results of tests carried out on power distribution line connections are incorporated in the recommendations. Properties of conductor metals and metal oxides are discussed. These illustrate requirements of recommended methods of making connections. Requirement for the proper selection of connectors, the proper preparation of conductors, and the proper application of fusion, compression, and bolted connectors are identified. Standards available on power line connectors are discussed to illustrate effective workman practices. Photographs of bad workman practices are included with explanations. Mathematical formula is developed for calculating correct die size for compression connectors. Amount of material available in connector and conductor are compared with area inside the suggested die for determining the correct die size. Performance identification of any type of connector installed in a power line is carried out by thermal imaging. Thermal images taken from few installed connectors are included and a procedure for assessing connector performance is suggested.
item: Conference-Full-text
The impact of distributed generation on transmission and distribution losses in Sri Lankan power system
(Institute of Electrical and Electronics Engineers, Inc., 2016-12) Priyangika, AAC; Wijayapala, WDAS; Banda, HMW; Rajapakse, A; Prasad, WD
Share of Non-Conventional Renewable Energy (NCRE), small hydro, wind, solar, bio-mass etc based electricity generation in Sri Lanka at present is 10% of the total annual generation. The Government of Sri Lanka has declared a national target of 20% from NCRE by 2020[1]. Most of NCRE power plants have been connected to the distribution network and are termed as Distributed Generators (DGs). With the increase of share of DGs, it affects system reliability, power quality and economic operation of the distribution network. This paper focuses on the impact of economic operation of transmission and distribution network due to distributed generation in Sri Lankan power system. Network simulation studies have been carried out for transmission network and for four grid substations to which many DGs have been connected. The analysis revealed that transmission network losses have reduced with increase penetration of DGs to the system while distribution network losses are dependent on the amount of DG capacities connected to the distribution network. However, there is a reduction of network losses when overall network is considered thereby giving financial benefit from DGs added to the system.