Browsing by Author "Rodrigo, A"

Now showing 1 - 20 of 27

item: Thesis-Full-text
Assesment of rooftop solar netmetering concept : consumer and utilty point of view
Nalani, JGS; Perera, HYR; Rodrigo, A
Global energy needs continue to grow, whilst fossil fuels still outstrip renewable energy in terms of supportive policies and subsidies. With growing concern towards climate change, many countries across the world are rethinking their energy strategy and incorporation alternative methods of energy generation. Of all the different modes of renewable energy technologies, Solar PV technology has caught the most attention. With environmental concerns and energy needs increasing, the world is promoting renewable energy technologies. Today, the PV systems price is decreasing, which gives it a competitive edge. The aim of this study is to research the viability of rooftop solar PV systems under certain circumstances. The study performs a cost beneficial analysis for the lifetime of the solar PV system making use of economic analysis on residential consumer perspectives and avoided cost analysis on utility point of view. The research concluded with several findings. Basically it concluded that the investment on Roof Top Solar is worthwhile when monthly consumption exceed 200 kWhs. Therefore, according to the present tariff structure and cost of solar PV Systems, Net Metering is not economical for monthly average consumption below 150 units. In utility point of view, it has been found that the reduction of avoided cost is rapidly increasing. But the rate at which the reduction of avoid cost increasing is decreasing and it becomes constant after 20 years. rooftop solar electricity generation cannot replace any marginal plant during the period of study concerned. There is no detailed study has been conducted in Sri Lanka in this particular area of study. The outcome of the research provides important and useful information for consumers, electricity utilities as well as the policy makers in energy sector.
item: Conference-Abstract
Card Sorting Method as a Participatory Approach to the Research Stage of City Branding Process: Understanding the City Experience from the Perspective of Stakeholders.
(Department of Integrated Design, Faculty of Architecture, University of Moratuwa., 2022-11) Rodrigo, A; Samarawickrama, S
The newest city branding approaches which identify cities as complex and uncontrollable entities, demands more stakeholder involvement that enables a participatory approach to city branding. As a city consists of many different stakeholders with diverse values and expectations of their own regarding the brand of a city, it is important to ensure that real stakeholder experience of the city is acknowledged, and the real perception of the city is not compromised in the city branding process. It is also important that branding strategy also includes all relevant actors and notjust the dominant or the compatible ones. While most academic approaches to city banding agree to this sentiment and discuss ’what’ to find out in order to ensure stakeholder involvement, they don't always mention ’how’ to find that information. As a participatory research approach there is a potential to use card sorting in subject areas other than UX, as card sorting methods identify user insights, perceptions and mental associations about user’s experiences. The objective of this study was to explore the potential of using Card Sorting, a main UXR method as a possible research method to understand the stakeholder perspectives about the city experiences to be used in the research stage of the city branding process. The selected card sorting methods Closed Card Sort, Open Card Sort and Hierarchical Card Sort uncovered insights about relationship between city experiences and stakeholders, stakeholder value systems about city experiences, negative and positive perceptions about city experiences and fundamental aspects of a city from the perspective of the stakeholders. The study revealed that different card sorting activities can be utilized to uncover what the city means to its stakeholders by understanding and acknowledging the stakeholders’ experiences, values and outlooks of the city.
item: Thesis-Full-text
Designing automatic load frequency control scheme for Sri Lankan power system
Kishokumar, G; Rodrigo, A
The Sri Lankan power grid is being operated at nominal frequency which is 50 Hz and steady state regulation window is 49.50 Hz to 50.50 Hz. There will be a frequency error left behind, during either demand or generation change as per system dynamics. Such error is generally corrected by secondary control regulation which is mainly done by verbal dispatch instruction originated from system control center. Hence, the regulation quality of grid frequency is highly depended on above said manual frequency corrective action which is executed by the Control Room Operator(CRO) back in the related power plants. The amount of frequency deviations within the operational limit, have been increased significantly during the last couple of years in Sri Lankan system. The aim of this study is to design and analyse the Automatic Load Frequency Control(ALFC) scheme for regulating secondary control spinning reserves based on persisting Area Control Error(ACE) values. Hence, MATLAB Simulink models are developed for primary and secondary regulations while addressing the unique constraints related to frequency regulation of Sri Lankan power system. Consequently, both the models are combined and the behavior of system frequency response with ALFC is studied in detail for different generation scenarios. The outcomes direct that, how exactly ALFC could be implemented in Sri Lankan power system while exhibit the enhancement of frequency regulation quality. The designed model and obtained results during this study could be used as base-case platform for implementation or further study of ALFC methodology for Sri Lankan power system.
item: Thesis-Full-text
Designing of railway electrification network configuration to minimize power quality issues : a case study for proposed Sri Lankan railway electrification
Mendis, WUK; Rodrigo, A
Electrified railway system is a better solution for the rapidly increasing congestion of traffic in urban areas and railway transportation has many advantages compared with other modes of land/air transportation. In Electrified railway system ,energy delivered to the train when needed(running), unlike the other modes of transportation (land, air, sea).According to the present railway passenger flow, suburban railway stations Panadura – Veyangoda sector was selected as high passenger density area which served 44% of all railway passengers and government has decided to electrified that sector first. The total track length between Panadura and Veyangoda is 156km. Due to the rapid acceleration and frequent starts of electric trains, there may large magnetic induction current in the power circuits and it may contribute to the grid voltage drop near urban areas. The energy flow back to the grid with regenerative braking and harmonics will added to the system. So, there are lot of power quality issues with electrified railway system and it is time to accept the challenge as Electrical Engineers. This research titled as “DESIGNING OF RAILWAY ELECTRIFICATION NETWORK CONFIGURATION TO MINIMIZE POWER QUALITY ISSUES: A CASE STUDY FOR PROPOSED SRI LANKAN RAILWAY ELECTRIFICATION” was carried out to find out an optimum voltage configuration to feed the railway system with minimum disturbing to the available power system. Electric train model was developed using Matlab Simulink to study the behavior of power distribution system while operating of the electric trains with current time schedule of the Sri Lankan Railways. The results were obtained and analyzed under the critical times at proposed railway substations .According to the results, optimum voltage configuration was selected in order to minimize the power quality issues to the utility grid.
item: Thesis-Abstract
Development of a cost based optimization technique for tower line design
(2015-07-06) Rathnayaka, RKAN; Wijayatilake, ACS; Rodrigo, A
Overhead high voltage and medium voltage transmission using tower lines is a common practice all over the world. Tower line construction projects integrate high costs while about 25 % of the cost is for tower metallic parts and 30 % of that is for foundation and erection [1]. Developed economies trying to achieve the cost optimization of tower lines by optimum spotting of towers at designing stage and several techniques have been developed in that purpose. In Sri Lanka, the process of planning, design and construction of transmission and medium voltage power lines is solely authoritative by Transmission Licensee and Five Distribution Licensees of the country. Until now, these six licensees and contractual parties, who are involved in power line construction process, do not use any systematic method for cost optimization in line design and construction. As the first step of this study, a research survey was done about available line design techniques, design criteria and constraints and available cost optimization techniques. Data were collected on available structure types, most recent structure costs, foundation costs and erection costs. This report will discuss the Dynamic Programming algorithm which gives the choice of available towers (structure) and sites of the towers for given survey data of a transmission line route, in such a way that the overall cost of running the line from one end of the route to the other, subject to all the design constraints, is a minimum. A software tool was developed which runs based on the developed dynamic programming algorithm. The software tool chooses and sites the towers, given the survey data of a transmission line route, available tower types and conductor parameters. By developed software tool, several experiments and re-designing were done using profile survey data of some constructed and existing 33 kV tower lines under Projects and Heavy Maintenance Branch-Region 01 of Ceylon Electricity Board (CEB) from year 2010. The results were compared with the initial designs and it has shown that a reasonable cost reduction can be achieved, and that cost reduction is varying with total line length, and characteristics of the line route.
item: Thesis-Full-text
Development of a transmission pricing methodology for Sri Lanka power system
Rajapaksha, RMIKK; Rodrigo, A
The electricity sector in Sri Lanka is governed by the Sri Lanka Electricity Act, No. 20 of 2009 (as amended), and the Public Utilities Commission of Sri Lanka (PUCSL) is empowered by the Electricity Act to regulate the electricity industry. Ceylon Electricity Board has license of Generation, Transmission and Distribution, while the Transmission Licensee is the Transmission System Operator and the Single Buyer. Five Distribution Licensees (DLs) buy electricity from the Transmission Licensee (TL). Tariffs and charges levied from the Distribution Licensees for purchasing of electricity from the Transmission Licensee are determined in pursuant to the Tariff Methodology approved by PUCSL. In addition to the five DLs there are a few customers directly served by the TL at 220kV and 132kV voltage level, but charged under the tariff imposed by DLs, since the presently approved tariff methodology is not properly address tariff calculation for the bulk customers connected at 132kV/220kV. In this research, different power market models, transmission pricing principles and methodologies in different power markets were studied first, followed by transmission pricing methodologies in different countries. The study evaluated three main methodologies which can be implemented in Sri Lanka: (i) embedded cost based, (ii) marginal cost based and (iii) composite cost based methodologies. By analyzing data in each proposed model, the best suited methodology for Sri Lanka is recommended to be the embedded cost based method. The new tariff scheme which is to be implemented should recover the cost of utility, simple, stable and easy to implement in existing framework. With this background it was proposed the embedded cost based tariff calculation model, as the most appropriate option for calculation the transmission tariff in Sri Lanka.
item: Thesis-Abstract
ENERGY EFFICIENT BUILDING MODEL: A Case study for Proposed SL ARMY Headquarters
(2015-10-22) Muhandiramge, GWASB; Rodrigo, A
The Sri Lankan Tri forces Headquarters with Ministry of Defence office complex are schedule to be located in one place at Akuregoda Baththaramulla. This building complex will be one of the largest office complexes in Sri Lanka and to be accommodated for different nature functions except routine official duties. Therefore more attention has been given to improve the architectural view of the entire complex. In the mean time less attention has been given for energy optimizations issues. When the proposed design is thoroughly studied, many possibilities are available to improve energy efficiency of entire complex with some simple modifications. In order to optimize the energy use for illumination system and HVAC system, this case study has been done for selected building area of the total complex. The part of the building complex is selected to do the research and selected area is developed as a separate building model. The research is mainly based on the finding of best wall to window ratio to optimize the energy consumption for illumination system and HVAC system of the selected building model. The calculation stages are done, maintaining the initial building parameters in human comfort zone as ASHRAE stranded and sun path over the location. The best orientation of the building model is obtained according to the north alignment. Then the condition of the building model is improved as an energy efficient model by replacing illumination system with LED luminaire, window glass with energy efficient low-e window glass and developing a building envelop. Financial evaluation is done to all proposed building models with compare to the existing design for energy consumption. Then the lighting power density (LPD) is calculated for each building model and made a comparison with the maximum LPD values published by Sustainable Energy Authority. The research methodology can be practiced in designing stage of any kind of a building to improve the energy efficiency effectively. It gives more opportunity for designers to develop more energy saving building environment, while maintain the human comfort in the same time.
item: Thesis-Full-text
Feasibility study on tubular skylights to be used in Sri Lankan office buildings
Kumara, BYBCP; Rodrigo, A
Tubular Daylight Guidance technology can deliver natural light in to a space in a building where daylight is limited with an internally mirrored pipe system using the phenomena called total internal reflection. This research has been conducted to identify the potential and feasibility of applying Tubular skylights in a Sri Lankan office building. The research has focused on the existing technologies and evaluated three models of Tubular skylights designed to be used in office applications. Computer simulations have been carried out to evaluate the light out puts of different lighting arrangements made with Tubular skylights. Energy evaluations have been carried out for the cases require artificial lighting to keep constant illuminance levels. Economic evaluations have been carried out with life cycle cost calculations to evaluate the economic feasibility.
item: Thesis-Abstract
The impacts of fuel price variation on Electricity pricing in sri lanka
(2015-06-26) Hapuarachchi, MSS; Rodrigo, A
This thesis report presents the analysis of the fuel price variation in the global context and review its impact to the power generation cycle of the country. Due to the delay caused in implementation of proposed generation plan during the period of 1990 to 2000, country suffocated from a power crisis where scheduled power cuts were common in nature. And further the Ceylon Electricity Board (CEB); the state owned institution which owned the monopoly of power generation, transmission is operating under a huge loss where it cannot cover its operating expenditures by selling electricity. This further created a huge financial crisis in the country where treasury has to fund in order to maintain the operation. In this analysis, impact of fuel prices on electricity pricing is analyzed for the period from 2013 to 2025. This analysis is carried out based on the Long Term Generation Plan developed by CEB in 2010. According to the analysis, generation cost shows a negative trend in real terms where the Generation cost reduces from 16.54 LKR to 9.96 LKR. This mainly due to fact that, power generation sector will be governed by coal power generation. And further, when power generation prices are determined subjected to current inflation rate prevail in the country, it is only 60% increase over the period of study (12 years) where in the past, electricity prices has shown a rise of more than 120% over similar period of time even though the published fuel prices are subjected to influences emerged from the political arena, where those were not calculated solely based on the cost of production. Further it is required to consider the fact that coal prices can be increased more than the forecasted values as Sri Lanka entered into the coal power business after 12years where it is supposed to come into the operation by 1998. As per the sensitivityanalysis carried out based on the fuel price variation, it is calculated that, even if the prices of both crude oil and coal are increased by 50% than the current predictions,generation cost will be less than the generation cost as at 2013 until the year 2025.
item: Thesis-Full-text
Improving distribution reliability through electricity tariff and their financial implications
Nagasinghe, DP; Rodrigo, A
Under price and revenue cap regulations, utilities are encouraged to minimize their costs which may even result low reliability. As the reliability of electricity supply has a very high impact on the country‟s economy as well as quality of life of people, regulators are required to address reliability at electricity tariff setting. The objective of this study is to identify different approaches the other countries use to provide incentives for distribution reliability improvement through electricity tariff and also to identify potential financial implications such mechanisms may have on the distribution utilities. These aspects are morefully described in Chapter 1. Chapter 2, 3 and 4, respectively includes an extensive literature review including the distribution reliability regulation mechanisms adopted by India, Philippine, Australia, Hungary and Great Britain, the mechanism identified in the Distribution Performance Standards Regulations (DPSR) of Sri Lanka and a mathematical reliability based pricing model called „Joint Pricing Model‟. Most of the countries use two incentive mechanisms, to provide incentives to improve the overall reliability of the utility and to compensate individual customers for poor service. Further, incentive mechanism is based on reliability target setting and measuring the utilities performance relative to the targets, where most of the countries set targets based on the historical performance of the utility. Based on overall reliability, most countries have mechanisms to provide a bonus for achieving the performance targets and a penalty otherwise and to compensate individual customers, all the countries studied use Guaranteed Service Levels (GSL) mechanism, where the customers are entitled to a direct payment if the reliability of their supply is poorer than the GSL. Further, the GSL payment rates are specified in the regulatory instrument (eg. regulation) itself. Chapter 5 gives the study methodology, which is formulated based on the findings of Chapter 2, 3 and 4. Further, based on the study methodology the financial implications on the distribution utilities under different incentive mechanisms are estimated, using distribution areas of Lanka Electricity Company as an example. The calculations of financial implications are given in Chapter 6. Chapter 7 gives a summary of the financial impact under each incentive mechanism and a further discussion on the incentive mechanisms. Chapter 8 gives the recommendations based on the study and the future work required in the area of study is given in Chapter 8.
item: Thesis-Full-text
Introducing open access and transmission pricing for sri lanka
Hasanka, KH; Rodrigo, A
In Sri Lanka the ownership of the essential infrastructure is retained with the state owned organizations such as Ceylon Electricity Board, Ceylon Petroleum Corporation etc. Most of such industries are vertically integrated monopolies because of the state owned infrastructure. Electricity transmission and distribution network businesses are natural monopolies because of its very large investment on asset base and the inability to duplicate the asset base. Even though the transmission and distribution network business are natural monopolies the electricity trading businesses can be carefully separated from the owner of the network. Thus the competition can be achieved. This dissertation discusses how the competition can be achieved through fully opening up the transmission network towards the wholesale competition. Further it discusses about a suitable methodology for the transmission pricing for Sri Lankan transmission network, an important aspect of opening up the transmission network. In identification of a suitable transmission pricing methodology it discusses the different transmission pricing methodologies practiced internationally. Characteristics of different transmission pricing methodologies are discussed and their applicability to Sri Lankan transmission network is discussed. Marginal Participation methodology in Rolled-in pricing model is further discussed since it satisfies the requirements of a better transmission pricing methodology. Transmission prices are calculated as per the above methodology using a power system analysis tool (PSS/E). Every node of the transmission system is given an hourly per MW transmission price and every generator/load connected to the transmission network is invoiced as per their agreed MW values with the network operator. Results of the transmission price calculations are analyzed and compared with the current pricing methodology. How the implementation of proposed transmission prices result in a better transmission system is discussed. The other factors required for a smooth operation of a Wholesale market model is briefly discussed and further studies can be done in those aspects.
item: Article-Full-text
Latency-Aware Secure Elastic Stream Processing with Homomorphic Encryption
(China Computer Federation, 2019) Rodrigo, A; Dayarathna, M; Jayasena, S
Increasingly organizations are elastically scaling their stream processing applications into the infrastructure as a service clouds. However, state-of-the-art approaches for elastic stream processing do not consider the potential threats of exposing their data to third parties in cloud environments. We present the design and implementation of an Elastic Switching Mechanism for data stream processing which is based on homomorphic encryption (HomoESM). The HomoESM not only elastically scales data stream processing applications into public clouds but also preserves the privacy of such applications. Using a real-world test setup, which includes an E-mail Filter benchmark and a Web server access log processor benchmark (EDGAR), we demonstrate the effectiveness of our approach. Experiments on Amazon EC2 indicate that the proposed approach for homomorphic encryption provides a significant result which is 10–17% improvement in average latency in the case of E-mail Filter benchmark and EDGAR benchmark, respectively. Furthermore, EDGAR add/subtract operations, multiplication, and comparison operations showed up to 6.13%, 7.81%, and 26.17% average latency improvements, respectively. Finally, we evaluate the potential of scaling the homomorphic stream processor in the public cloud. These results indicate the potential for real-world deployments of secure elastic data stream processing applications.
item: Thesis-Full-text
Methodology to determine the maximum demand of multi category bulk electrical installations
(2015-10-26) Rajapaksa, SAC; Rodrigo, A
Conventional method of maximum demand determination of a multi category bulk electrical installation at planning stage is done by using several rules of thumb, in which maximum demand and time at which maximum demand occurs cannot be estimated accurately. This incorrect maximum demand estimation caused for wrong transformer and backup power capacity estimation, wrong cable and switchgear selection, inefficient performance of transformer, incorrect statistics, etc. In this research, a methodology is proposed to determine the maximum demand of multi category bulk electrical installation using its entire kVA profile. This entire kVA profile of multi category bulk electrical installation is generated through a database of kVA profiles in which averaged normalized kVA profile for each installation categories have been defined along with their electrical power loading characteristics. Multi category bulk electrical installation can be considered as a combination of several single category bulk electrical installations. Hence, to determine the entire kVA profile of a multi category bulk electrical installation, averaged normalized common kVA profiles which represent each category will be added together with multiplying them by their individual calculated maximum demand. To compile the database of averaged normalized common kVA profiles, kVA profiles (each contains kVA values of one month logging period with 15 minute intervals) of 500 numbers of single category bulk electrical installations have been considered as the sample. The sample is preprocessed, normalized and then clustered using Hierarchical Clustering Algorithm. By using square sum of error of each clusters and Knee point criterion, seventeen numbers of unique kVA pattern classes were identified. Then averaged normalized kVA profiles were derived for each pattern class and map them up with example single category bulk electrical installations and their characteristics to compile above said averaged normalized kVA profile database. Visual basic programming and Matlab software is used to execute above said research work. This proposed methodology has been verified considering a multi category electrical installation and proposed methodology can be considered as an acceptable one to determine the maximum demand of multi category bulk electrical installations. This methodology can be further improved by compiling averaged normalized kVA profile database for each installation categories separately. Additionally, this research can be further improved as a required tool for load forecasting, demand-side management, system planning, distribution system loss estimation and better tariff design, etc.
item: Thesis-Full-text
Modeling of transmission tower grounding system
Karunapala, PMAU; Rodrigo, A
Performance of power transmission lines has a great impact on reliability aspects of a particular power supply system of a country. Unreliable power transmission lines can even leads to total power failures resulting with great financial losses. In order to improve the withstand level of transmission lines, to reduce line lightning trip-out rate and the accident rate grounding resistance in grounding grid of transmission line tower should be effectively ameliorated. This thesis is a study of a 132 kV transmission line tower grounding system. Several standards are developed for designing a grounding system for AC substations and building installation but it is harder to find references for transmission line tower grounding specially when the soil condition is poor. The transmission line is routed over a high resistive soil, where the requirements from the design standard can not be fulfilled. During normal conditions, each tower can be properly grounded to earth with ground electrodes, but for high soil resistivity conditions there should be a properly designed earthing arrangement for transmission towers. By studying different practical earthing method being using all over the world for high voltage transmission towers, a suitable solution can be found. A Practical earthing design for different soil types was proposed for the modeling and simulation to find a suitable eathing design for Ceylon Electricity Board transmission lines specification. This thesis will discuss the Finite Element Method (FEM) developed for grounding analysis. Computer software analysis packages can be used to assist in earthing design by modeling and simulation of different earthing configurations. FEM method of ETAP‟s Ground Grid Design Assessment software is used for modeling the new tower earthing design for different soil types based on soil resistivity values. For the each earthing design type theoretical verification of the earth resistance values was done using Thapar-Gerez equation which is developed for the calculation of earth resistance values.
item: Thesis-Full-text
Modelling of lighting surge propagation in railway track and propose an effective protection system
Jayatunga, WI; Rodrigo, A
The Signalling Network is considered as the brain of the Railway Department, which ensures the safety of the train operations as well as for enhancement of the capacity of trains in the network. The track circuit is the basic logic circuit, which uses in all the other major circuits for selecting and locking routes for trains. Since these track circuits are directly connecting to the rails, it is critically important to protect those track circuits and other expensive equipment connected via track circuits from direct and indirect lightning surges through rails. Rails are the main invasion path of lightning surge into the railway signalling system.So far, the railway department has not properly standardized the surge protection devices attached to the signalling system and it directly affects the railway operations and train delays, which may cause social disruption. Since it is among the major concerns of the signal department is struggling with; this thesis addressed the issue by analysing characteristics of the rail and connected circuit components and all possible paths where surges can be entered into the system. Simulation has done by using the rail model prepared using PSCAD software and ground test results were validated with them.Direct and indirect surge currents were calculated theoretically for 50 kA, 100 kA and 200 kA surges of 10/350 μS and 8/20 μS by applying the calculated surge currents to the above rail model. Induced surge currents of injected rail and induction rail were obtained graphically for different rail lengths. Finally, by analysing all above results and protection levels of different surge protecting devices, this thesis suggests Category A type surge-protecting device according to IEEE C62.41.2 standard as the best suitable and economical type for including in the track circuits to avoid damages through surge currents via rail linesii
item: Thesis-Full-text
Optimum reactive power compensation & voltage control using static var compensator for grid substations
Kumarasinghe, SCD; Rodrigo, A
As the volume of power transmitted in transmission lines increases, maintaining high quality and reliable power supply is required. Modern power systems sometimes operate with heavily loaded lines resulting in power system to work under condition of higher power loss and higher voltage deviation. Sometimes, it may lead to voltage instability or system collapse. The emergence of power electronic based FACTS technology such as Static Var Compensator (SVC) has been of great help in improving the operation of power systems as it reduces the power system instability problem, power losses and voltage deviation. Placing FACTS devices at proper locations can serve the purpose of improving voltage levels and reducing losses in the system. Due to huge investments associated with SVC, a proper analysis and planning is required before the installation. The objective of the study is to use optimization technique for minimization of power loss and voltage deviation along with installation cost calculation for the selection of SVCs for grid substations. Whole Sri Lankan power system has been modeled using the PSS/E (Power System Simulator for Engineers) software. The voltage deviation of all the buses in the network and the total active power loss in all the transmission lines are analyzed with SVCs and without SVCs using PSS®E software. Further, single line outages are considered as contingencies for optimal placement of SVC. Finally, optimum combinations of SVCs are selected to minimize the system voltage deviations and active power loss of transmission lines.
item: Thesis-Full-text
Optimum reactive power compensation methodology to minimize system overvoltage conditions
Perera, CKS; Rodrigo, A
Sri Lankan Power system has experienced power frequency over voltages at steady state conditions predominantly at New Anuradhapura, New Chilaw and Chunnakam Grid Sub Stations. New Anuradhapura being connected to the lengthiest 220kV transmission lines from Kothmale (163km) and New Chilaw being connected to the Lakvijaya Power Station, which accounts to the highest capacity of national generation contribution and Chunnakam having long distance radial connection are the root causes for the issue. Currently the network overvoltages are mainly monitored at 220kV level due to sensitivity of the protection schemes implemented on the 220kV network equipment. Eg v/f, overvoltage protection, but all network equipments are vulnerable to overvoltage conditions despite their operation voltage level. In 27th September 2015, the most destructive event in terms of overvoltage occurred in the Sri Lankan power system initiating with tripping of Lakvijaya Gen 03 and ultimately causing a blackout. Post failure studies concluded with stressing out lack of reactive power compensation for overvoltage scenarios in present network topology. In power system, the reactive power compensation is important for system voltage profile. This is also helpful to power factor improvement and loss reduction. This study illustrates effectiveness of dynamic stability with integration of variable shunt reactors and static var compensators to the existing network topology, further studies are carried out to assess the effectiveness of disconnecting selected circuits to minimize overvoltage problem.
item: Thesis-Full-text
Optimum use of solar inverter by feeding reactive power at the night
Kurunayakage, KN; Rodrigo, A
Due to the significant increase in price of Grid Electricity, many countries are switching to Renewable sources. With the expanded Solar Net Metering system which is approved by the Ceylon Electricity Board in Sri Lanka, Domestic consumers and all Commercial consumers will be benefited after installing such a renewable energy system directly connected to the grid. As a developing country Sri Lankan electricity system has many issues related to the under voltage. Therefore by improving the voltage profiles installation of capacitor banks either in customer end or utility side is being promoted. “The PV inverters that are not utilized at the time of night peak can be operates in feeding reactive power to eliminate the low voltage occurrence during the night peak.” This postgraduate research thesis describes the above mentioned proposal with theoretical background. An algorithm was developed to calculate operating power factors for existing PV inverters in the particular feeder which is having under voltage problems. The software was developed to calculate the operating power factors of any system with existing system information. Economic Evaluation was carried out by proposing a reward scheme for customers and benefits to the utility were discussed. The net saving to the utility was positive, according to the case study result. Proposed algorithm was discussed with a case study and the results are verified by modeling the same in SynerGee. Finally, utilizing distributed PV inverters at night peak by feeding reactive power, low voltage issues and line losses can be reduced in that particular feeder. This study was proposed to utility side where the problem identification and the relevant solution can be made accordingly.
item: Thesis-Abstract
Potential of generating power out of rice husk and its financial viability
(2015-01-07) Perera, PIAS; Rodrigo, A
Due to intense fossil fuel dependency on energy generation in the world, cost of energy has a greater bearing on the price of fossil fuels. Most of the countries in the world are suffering due to this and Sri Lanka is no exception. It is in this context, promotion of biomass as a renewable source is so vital to the country. Even though biomass plays a greater role as a source of primary energy in the country, its contribution towards power generation is negligible. Rice being the staple food of the country as well as the crop with highest land area under cultivation, rice husk produced in paddy processing was found to have a significant potential in power generation. Currently, rice husk has not been identified as promising source of energy for electricity production in the country. Hence, the purpose of this research was to investigate the possibility of using rice husk as a viable source of power generation in the country thereby releasing part of the burden on country’s fuel bill. Annual paddy production of the country remains slightly above 4 million metric tons with 800,000 metric tons of rice husk being produced as a byproduct in paddy processing. If assumed total rice husk production is tapped for energy generation, total energy potential comes to around 2,176 pJ per annum at the conversion rate of 20%. Since significant portion of this energy is currently being harnessed for thermal applications, potential for electricity generation out of rice husk is restricted somewhat. However, the findings of this research shows that still 30% of rice husk produced in the country is available for exploitation in power generation with a potential of about 180GWh per annum. Greater portion of this electrical energy can be tapped in the districts of Ampara, Polonnaruwa, Anuradhapura and Kurunegala because of higher paddy production and milling capacities in these districts. However, the scale of power generation is limited to 1MW to 2MW maximum plant capacities for above districts while small scale plants of the order of 40kW showing better financial viability under Net Metering Scheme currently in force.
item: Thesis-Full-text
Real time dynamic thermal rating method to uprate the ampacity of overhead transmission lines in Sri Lanka
Sinniah, R; Rodrigo, A
Real time dynamic thermal rating (RTTR) is a smart-grid technology, which allows to utilize the overhead line conductors by increasing the current carrying capacity of the line based on real time weather data. Traditionally, Static thermal rating (STR) calculates current rating based on ‘Worst case weather conditions”, which is used in Ceylon Electricity Board (CEB) as well as most of the utilities around the world. These assumptions may reduce the actual line capacity whenever real weather conditions are less stressful.The optimal current carrying capacity(CCC) of a line is primary determined by the critical span along the line route. Therebefore the sag of the line has been analysed in detailed to identify the critical span with help of PLSCADD Software. Then, the real time weather data have been applied and RTTR values for interested transmission lines has been calculated. In this research, current rating using real time weather cases have been calculated for selected transmission lines in Sri Lanka and compared the results with static thermal rating methods. A software based RTTR model was also developed in VBA platform in order to calculate the real time CCC. This software interface can be used to analyse entire transmission network of Sri Lanka to calculate weather based current ratings.