Master of Science in Electrical Installationshttp://dl.lib.uom.lk/handle/123/562024-03-28T15:05:12Z2024-03-28T15:05:12ZEstimation of earth electrode resistance of antenna structures located in non-homogenous geographic terrain using finite element analysis and predictive modellingSubasinghe SAVDhttp://dl.lib.uom.lk/handle/123/213552023-10-13T00:28:34Z2022-01-01T00:00:00ZEstimation of earth electrode resistance of antenna structures located in non-homogenous geographic terrain using finite element analysis and predictive modelling
Subasinghe SAVD
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.
2022-01-01T00:00:00ZA dynamic load shedding scheme for maintaining system frequency stability with the increasing renewable energy penetrationHerath BHMSThttp://dl.lib.uom.lk/handle/123/175972022-09-28T14:59:26Z0020-01-01T00:00:00ZA dynamic load shedding scheme for maintaining system frequency stability with the increasing renewable energy penetration
Herath BHMST
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.
0020-01-01T00:00:00ZEnvironmental monitoring system for military armouriesRanatunge KGJPhttp://dl.lib.uom.lk/handle/123/203922023-11-07T09:15:20Z2021-01-01T00:00:00ZEnvironmental monitoring system for military armouries
Ranatunge KGJP
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.
2021-01-01T00:00:00ZDevelopment of a guideline for designing economical and effective retrofit led street lighting system for Sri LankaMuthuransi LWNhttp://dl.lib.uom.lk/handle/123/204052023-11-08T04:38:34Z2021-01-01T00:00:00ZDevelopment of a guideline for designing economical and effective retrofit led street lighting system for Sri Lanka
Muthuransi LWN
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.
2021-01-01T00:00:00Z