Master of Engineering in Electrical Engineering
http://dl.lib.uom.lk/handle/123/709
2024-03-29T04:11:55ZDevelopment of coordinated voltage control mechanism for MV networks with large scale solar penetration
http://dl.lib.uom.lk/handle/123/15886
Development of coordinated voltage control mechanism for MV networks with large scale solar penetration
Peiris MKD
With the rapidly increasing solar PV penetration to the Utility Distribution Network (UDN) over the past decade, numerous operational challenges including Power Quality (PQ) problems have become substantial compared with the conventional UDN globally. Primarily, solar photovoltaic (PV) systems were connected to the UDN via Low Voltage (LV) side, however, global trend has been advanced to extract solar energy through Medium Voltage (MV) networks up to date via large scale solar farm integration.
Steady state voltage rise in the distribution feeders is reported as one of the main constraining factors for limiting solar PV deployment in LV and MV networks. In Sri Lankan context, recent studies proved that over voltages stay unavoidable in LV networks with high solar PV penetration. Further, preliminary system studies has shown that over voltages will give rise due to the connection of proposed 1 MW Solar Farms at MV level under the “Battle for Solar Energy” program.
This thesis is a comprehensive study to identify the PQ issues correlated to such MV networks, especially asses the over voltage occurrences during the day time where solar penetration at its maximum. A coordinated decentralized control mechanism is adapted to control the over voltages and maintain the voltage levels within its stipulated limits. Coordination between two decentralized voltage controllers; reactive power control of solar PV inverter and distribution static compensator (DSTATCOM), is proposed to harness the maximum amount of clean energy into the UDN avoiding voltage violations, splitting the MV network into multiple controllable zones.
The coordinated voltage control mechanism was modeled using DIgSILENT PowerFactory simulation platform for IEEE 33-bus radial network, which was further extended to the Mauara feeder of the Embilipitiya Grid Substation of Sri Lanka in order to verify the mitigation of over voltages due to large scale solar penetrations. Finally, the influence of the DSTATCOM location and the dead band voltage of the PV inverter on the voltage profile of the Mauara feeder were analyzed.
2019-01-01T00:00:00ZDevelopment of a solar PV capacity addition plan for Sri Lanka to maximize economic benefits
http://dl.lib.uom.lk/handle/123/15885
Development of a solar PV capacity addition plan for Sri Lanka to maximize economic benefits
Rathnayake RMMR
Sri Lanka has set various targets to integrate renewable energy-based power plants into the main grid while keeping a stronger focus on solar photovoltaic (PV) and wind power plants. A proper economic justification is not available, specially for targets set on increasing the capacity of solar PV systems.
This research addresses this drawback by quantifying the economic costs and benefits related to electricity generated by solar PV systems under penetration of different solar PV capacities. An optimum capacity which maximizes the net economic benefits was derived as the final output of the research.
Sri Lankan power system at generation level was modelled using a dispatch modelling software (PLEXOS) to obtain displaced fossil fuel and variable operation and maintenance (O&M) costs, by electricity generated by solar PV systems. A spreadsheet-based economic benefits evaluation model was used to calculate the present value of net benefits of the analysed solar PV penetration levels.
2019-01-01T00:00:00ZSound source localization of human ear in a planner surface using ...
http://dl.lib.uom.lk/handle/123/11354
Sound source localization of human ear in a planner surface using ...
Jayaweera, WGN
The human auditory system is a collection of technical theories and mathematical equations in the context of human sound source localization process. Also, according to the developed human ear models, under the disciplines related to engineering and biomedical science, the electrical ear model can further be used in deriving the biological human auditory system mathematically.
In this research, the outer ear, middle ear, inner ear related to both ears and the brain are considered as the total human auditory system. In developing the mathematical model of human auditory system, electrical model of human ear is considered and using MATLAB powersim library mathematical model is developed.
Experiment -1 is conducted to collect raw data for the proposed human auditory model. In the experiment, a dummy head with two condenser microphones to record the left and right ear sound signals is selected and placed in middle of circles having 1m, 2m and 3m radius. Then 1 kHz and 5 kHz distinct sounds are played at 24 different locations and incident sound signals as a stereo signal is recorded using desktop computer.
Experiment -2 is conducted to investigate the individual ability to predict the direction of a sound source. Ten numbers of samples of young adults from the age group of 20 to 30 years are taken into the experiment and their responses for localization cues are recorded. The experiment is also conducted for different sound source locations such as 1m, 2m and 3m and different source frequencies of 1 kHz and 5 kHz.
With the raw data collected under experiment-1, sound signal is processed through each ear of the proposed mathematical model using MATLAB and using Interaural Time Difference (ITD) and interaural Level Difference (ILD), sound source localization is done. In comparison with the actual human sound source localization analyzed under the experiment 2, the proposed model is verified.
The results show that the proposed mathematical biological auditory system obeys the characteristics of real human auditory system at frequencies less than 1500 Hz, while the sound source localization algorithm is a combination of interaural time and level differences. On the other hand, at higher frequencies, the model deviates from the real human auditory system characteristics,
The proposed mathematical model of human auditory system follows the real human auditory system behavior at frequencies less than 1500Hz, with the combination of ILD and ITD sound localization algorithms. Also, at higher frequencies, the model deviates from the real human auditory system and the actual sound localization algorithm at higher frequencies is yet to be investigated.
2015-09-16T00:00:00ZModeling the contact resistance of different Architectures
http://dl.lib.uom.lk/handle/123/10986
Modeling the contact resistance of different Architectures
Hettiarachchi, RM
The performance of electrical contacts, which are inevitable in the electricity distribution system will affects the power quality, reliability and hence the level of customer satisfaction. Making a successful contact depends on the design of a contact and proper workmanship. Thus, the knowhow on the behavior of a contact plays a major role in every aspect of making a successful electrical contact.
The research undertaken was to study the behavior of electrical contacts having basic architectures and to develop a model to represent the resistance of contacts during loading. Basic architectures of current contacts were identified and resistance between two contacts members were measured against the load applied to it.
A special testing apparatus was designed and fabricated for the study. This consists of a Compression Test Cell, Load Cell and a micro ohm meter. A Thermal imaging camera was used for observing Temperature Profiles.
Rod tip architecture was initially examined under three basic tip angles 300, 600and 900. Then parallel rod architectures were examined for the study and developed model for the resistance.
An empirical model for the resistance for the parallel rod was developed and that was theoretically extended for the stranded wire. The research outcomes of the study suggest modern improvements in contact designs and potential workmanship practices in making successful contacts.
2015-07-06T00:00:00Z