Electrical Computer Engineering

Permanent URI for this collectionhttps://etd.hu.edu.et/handle/123456789/74

Browse

End date: 2019

Search Results

Now showing 1 - 10 of 18
  • No Thumbnail Available
    Item
    EVALUATING CRYPTOGRAPHIC ALGORITHMS OF AUDIO AND VIDEO DATA FOR SYSTEM RESOURCE CONSTRAINED OF IoT DEVICES
    (Hawassa University, 2019-10-27) WAGARI BERHANU
    We are living in an internet period in which digital data exchange in electronic way has progressed tremendously and securing information has become a challenge. Unless a creative means of securing information has been developed, the problem will be vast and limitless. In a bid to keep the pace of the era, cryptography plays an important role in information security systems. Cryptography is a process of creating information indecipherable to an unauthorized person. It is quite a well-known fact that IoT (Internet of Things) is a system of interrelated computing devices or digital machines is the ability to transfer data over a network. the devices that used in IoT is low power devices for this reason, the system resource is one sever issues. To do so various cryptographic algorithms used in IoT devices. Meanwhile, these algorithms consume a significant amount of computing resources such as CPU time, memory and computation time. This thesis provides evaluating AES, Blowfish, RSA, Trivium and Elliptic Curve Cryptosystems based on system resource usage to securing IoT device communications on the basis of encryption time, decryption time, throughput, CPU time, power efficiency and memory usage in audio and video data using Java as the programming language to develop algorithms. The result obtained shows that AES has better performance with encryption time, decryption time, throughput rate, CPU time, power efficiency and memory usage with audio and video files in various format
  • No Thumbnail Available
    Item
    PERFORMANCE COMPARISON OF CHANNEL MODELS FOR UFMC SYSTEM
    (Hawassa University, 2019-08-29) TILAHUN BELAYNEH MAMO
    This paper presents the bit error rate (BER) vs. signal-to-noise (SNR) ratio performance of channel models under UFMC system with 32- FSK, PAM, DPSK, 4-QAM, 16-QAM, 32-QAM, 64-QAM and 128-QAM modulation. In future it is believed to be more challenging and complicated with the evolution of different types of fading model. These types of fading models determined in urban and rural areas. Rayleigh fading model is considered to be most common fading model, found in urban environment for non-line of sight. Rician fading consists of line of sight communication and found to be more applicable for satellite communication. Nakagami fading model is mostly suited for urban multipath propagation and it is sought to be most practical model, specially used in mobile communication. In order to achieve error free signal at the receiver the choice of modulation scheme should be done wisely. The combination of best efficient modulation scheme along with the block coding helps in getting the signal error free at the receiver. The condition of signal is decided by SNR v/s BER (bit error rate) simulation. Our main objective is to get error free result at the receiver, so for this different data transmission techniques are used to transmit the data from transmitter to receiver in various fading channels under different modulation schemes. Effect of shape factor on Nakagami fading is also covered in this thesis to get efficient results. The BER performance was to compared with Additive White Gaussian Noise (AWGN), Rayleigh-faded, Nakagami-m faded and Rician-faded channels. It has been further concluded that the BER vs. SNR performance graph in AWGN channel environment is better than that in Rayleigh, Nakagami-m and Rician-faded channel. It is also observed that by varying the standard-deviation of the channel, the BER vs. SNR performance graph is not going to be affected if the channel is considered Rayleigh-faded. In this paper we address a new aspect of UFMC system performance by investigating its capability to overcome the channel fading channels’ effects and to provide good and reliable performance levels overcome these channel effects.
  • No Thumbnail Available
    Item
    Integrated energy optimization of smart home appliances with cost-effective energy management system (Case Study: Mid-Size Residential Home at Hawassa City
    (Hawassa University, 2019-10-27) Tesfahun Molla
    With the development of smart grid technology, residents have the opportunity to schedule their power consumption pattern in their home by themselves for the purpose of minimizing electricity expense, reducing the peak-to-average ratio (PAR) and peak load demand. The two way flow of information between electric utilities and consumers in smart grid opened new areas of applications. In this thesis, a general architecture of home energy management system (HEMS) would be introduced in a home area network (HAN) based on the smart grid scenario and then an efficient scheduling method for home power usage would be proposed. The energy management controller (EMC) receives the demand response (DR) information indicating the Time-of use electricity price (TOUP) through the home gateway (HG). With the DR signal, the EMC achieves an optimal power scheduling scheme that can be delivered to each electric appliance by the HG. The rooftop photovoltaic system used as local generation micro grid in the home and can be integrated to the national grid. These results in reduction of electricity bill and when solar energy production is more than the demand of the home, the excess energy could be exported to the national grid. Accordingly, all appliances in the home operate automatically in the most cost-effective way. Detail explanation and discussion of four scheduling techniques would be designed under TOUP. To calculate the fitness function; two powerful swarm intelligence based Meta-heuristic algorithms i.e. Grey wolf optimizer (GWO) and Particle swarm optimization (PSO) algorithms had been used. Finally, detail comparison and analysis between proposed methods and algorithms could be carried out. To display the result, MAT LAB 16(a) software environment would be used
  • No Thumbnail Available
    Item
    RESOURCE POTENTIAL ASSESSMENT AND OPTIMAL DESIGN OF PV/WIND/BATTERY/ DEISEL GENERATOR BACK-UP HYBRID ENERGY SYSTEM FOR REMOTE AREAS
    (Hawassa University, 2016-10-22) MESFIN JARISO
    Off grid hybrid systems have been attracting to supply electricity to rural areas in all aspects like, reliability, sustainability and environmental protections, especially for communities living far in areas where grid extension is not appropriate. Hybrid renewable set-up indicates that combinations based on the renewable sources could be applied simultaneously to supply energy in the form employed in an off-gird supporting with battery storage and diesel generator as backup systems. In this thesis photovoltaic-wind turbine-battery bank and diesel generator have been optimally sized, simulated and optimized for the rural community of Addis Boder village in the southern regional State, Ethiopia. Primary load demand of 142KWh/day, peak load of 26kW, deferrable energy is about 27kWh/day, and deferrable peak load of 3.6kW was involved during optimization of the power system. Well known HOMER modeling tool have been used to design the off-grid system. Solar and Wind energy are considered as primary sources to supply electricity directly to the load and to charge battery bank when excess generation is happened however in peak demand times diesel generator could also be engaged. Regarding solar energy potential there is no accurately recorded solar radiation database in the country, instead only sunshine hour data was available. Empirical formulas are used to estimate the solar radiation from available sunshine duration data. This result is compared with the data collected from NASA and it is found to be nearly the same. Consequently, for this study the calculated solar radiation is used for modeling the hybrid system. During the design of this power system set-up, the simulation and optimization was done based on the electricity load, climatic data sources, economics of the power components and other parameters in which the NPC has to be minimized to select an economic feasible power system. The results obtained from the software give numerous alternatives feasible hybrid systems with different levels of renewable resources penetration which their choice is restricted by changing the net present cost of each set up Power schemes with less NPC, less COE, higher renewable fraction, less capacity shortage, smaller excess electricity and minimum fuel consumption would be suggested as optimum system. It is concluded that besides electricity provisions, the role of a standalone hybrid system in protecting the environment from degradation, the improvement of life of people living in rural area, development of clean energy, and the future situation regarding fossil fuel sources should be taken in to account. Taking these issues into account the free solar and wind energy of the country should be utilized to improve the quality of life of the communities living in rural areas
  • No Thumbnail Available
    Item
    OPTIMAL PLACEMENT OF PHASOR MEASURMENT UNIT FOR STATE ESTIMATION IMPROVEMENT
    (Hawassa University, 2017-10-15) KINFE NEGASH
    Installation of modern sensing devices is an integral requirement in the transition of a conventional power grid to smart grid. Phasor measurements synchronized through GPS presents one such alternative to enhance the monitoring and control feature in the power grid. Due to the high financial implications, these units should be deployed optimally in the grid. The methods reported in the literature for optimal placement usually provide multiple solutions. This thesis presents criteria of optimal solution for state estimation enhancement. The criterion is based on sensitivity analysis and analyzing way of increasing the rank of the gain matrix to install the phasor measurement unit on improving the state estimation results. A reduced form integer linear Programing algorithm is to be formulated according the criterion given for optimal placement problem for improved state estimation. The reason behind this is that all the downstream applications of contingency analysis; steady-state, voltage, and dynamic as well as the optimal power flow are dependent on the accuracy of the state estimation results. Because of its key role in energy management system, state estimation is set to be a vital function in the development of smart grid. For the Process Power education tool (PET) and Matlab are used and validated on testing on IEEE 14-bus system as a base case and a southern region 21-bus system as a study case
  • No Thumbnail Available
    Item
    OPTIMAL EXPANSION PLANNING OF DISTRIBUTION NETWORK WITH DISTRIBUTED GENERATION BY UTILIZING GRID-BASED MULTI-OBJECTIVE HARMONY SEARCH ALGORITHM (CASE STUDY: DEBREMARKOS DISTRIBUTION NETWORK)
    (Hawassa University, 2019-04-25) TAKELE FEREDE AGAJIE
    Electrical energy plays a vital role in the socio-economic development. To combat for the power system profile problems, distribution substation needs to be established considering future expansion due to urbanization. Debre Markos (D/M) distribution network needs expansion planning to meet the growing load demand. To evaluate the capability of the existing distribution network and to supply reliable power for future expansion, demand forecast for the years 2017/18-2022/23-2027/28 has been performed by using trend forcasting technigue withl east sequre approximation and evaluating the load flow by using backward-forward sweep load flow. According to the results, the existingnetwork cannot meet the existing load demand and it has major problems of increased voltage deviation and power loss. In this thesis, D/M distribution network expansion planning considering future demand growth and distributed generation placement and sizing is carried out using Grid based Multi-Objective Harmony Search Algorithm (GrMHSA). The total real power loss (Pl), total reactive power loss (Ql) and total voltage deviation (VD) at the target year for the base case by taking the existing line and the projected bus data are 7434.9kw, 7391.8kvar and 58.6952p.u for D/M Feeder 3 and 470.7058kw, 404.5524kvar and 6.4412p.u for D/M Feeder 4 respectively. After applying GrMHSA optimization technique for DG sizing and placement, the total Pl, total Ql and VD at the target year are 95.398kw,124.979kvar and 0.479p.u for D/M Feeder 3 (F3A and F3B) and 30.811kw, 37.727kvar and 0.533p.u for D/M Feeder 4 respectively
  • No Thumbnail Available
    Item
    Reactive Power Compensation and Harmonic Mitigation of Power Distribution Network Using Shunt Active Power Filter Based P-Q theory (Case study: Hawassa substation-2)
    (Hawassa University, 2017-04-09) Tahir Kedir
    Traditionally, the harmonic distortion and reactive power has been reduced using passive LC filters. However, the application of passive LC filters for reactive power compensation and harmonic mitigation results in parallel resonances with the network impedance. It is poor flexible for dynamic compensation of different frequency harmonic components.This work presented a scheme for reactive power compensation and harmonic mitigation of Hawassa substation-2 using shunt active power filter(SAPF), which is based on instantaneous p-q theory. The filter is identified, it automatically adapts to changes in the network and load fluctuations to mitigate the harmonics and reactive power issues. It is able to produce almost unity power factor and mitigate the total harmonics distortion (THD) to meet specified power quality standards. The performance of the SAPF depends mainly on the p-q theory to compute reference current and hysteresis band current controller to generate pulses for switching pattern of the inverter. The advantage of instantaneous p-q theory shows that it is instantaneous and works in time domain. MATLAB/Simulink computer simulation (version R2016a) is used as a simulation tool for this study. The simulation results before and after the compensation is compared to specified IEEE 519-1992 power quality standards.In three phase, three wire configurations, the result shows that THD in the load current is reduced from 37.46% to 3.56% and THD in the source voltage is reduced from 26.91% to 2.74% and power factor is improved from 0.869 to 0.949 under non ideal voltage source conditions while the reactive power is reduced from 1,178.04KVAr to 746.05KVAr
  • No Thumbnail Available
    Item
    ASSESSMENT OF RELIABILITY ASPECTS IN POWER DISTRIBUTION SYSTEM AND DEVELOPMENT OF REINFORCEMENT MECHANISMS (CASE STUDY: SHASHEMENE CITY DISTRIBUTION SYSTEM
    (Hawassa University, 2019-10-17) KABTAMU KETSELA
    A stable and reliable electric power supply system is an inevitable pre-requisite for the technological and economic growth of any nation. Due to this, Ethiopian electric utility (EEU) must strive and ensure that the customers’ reliability requirements, which are met at the lowest possible cost. EEU should have their own reliability improvement strategy depending upon their needs and requirements of their customers. Although there are notcomplete methods in managing all reliability issues, utilities can maximize network performance and better serve customers by carefully addressing trouble prone areas. In order to achieve this objective, reliability factors based reliability analysis is performed under Electrical Power System Analysis (ETAP) software environmentIn this thesis, it is observed that different reliability reinforcement mechanismshas been undertaken to evaluate predictive reliability analysis for the future system. Using line reconductoring for wendogent feeder the SAIFI, SAIDI and EIC reduced by 12%, 7.5% and 32% respectively. For shashemene city feeder using Autoreclosure SAIFI, SAIDI and EIC reduced by 45%, 35% and 35 % respectively. For Arsinegele feeder using separate CB the SAIFI, SAIDI and EIC reduced by 9.7%,6.4% and 8.8% respectively and water pump feeder using covered conductor SAIFI, SAIDI and EIC reduced by 14.9%,9% and 9.8% respectively. Reliability indices of shashemene substation show the substation is unreliable as compared to standard practices and Ethiopia’s reliability requirement
  • No Thumbnail Available
    Item
    PSO Based Reactive Power Optimization of Utility Grid With Wind Generation
    (Hawassa University, 2019-10-22) HAILU TIBEBE MENGISTU
    Reactive power is critical to the operation of the power systems on both safety and economic aspects. Irrational distribution of the reactive power would severely disturb the power quality of the power systems and increases the transmission loss. Reactive Power Optimization (RPO) is defined as the minimization of active power loss by controlling a number of variables. Reactive power optimization problem is a nonlinear optimization problem and has both equality and inequality constraints. In this thesis, the Particle Swarm Optimization (PSO) algorithm and Mat-power toolbox are used to solve the reactive power optimization problem for generation/distribution system with wind generation (WG) plant. The proposed method minimizes the active power loss in a practical power system as well as determines the optimal placement of a new installed WG (Wind Generation). The practical 21-bus, power distribution network of Southern Region is used to evaluate the performance.
  • No Thumbnail Available
    Item
    PERFORMANCE COMPARISION OF PILOT-BASED CHANNEL ESTIMATION METHOD IN OFDM SYSTEM OVER FADING CHANNEL
    (Hawassa University, 2019-10-11) HABTAMU ABEBE
    Wireless channel is unknown and inclined to time dispersion, which causes inter symbol interference (ISI) and fading. OFDM is one of the most capable core technologies in the fourth generation of wireless communication systems. OFDM has the advantage over the conventional single-carrier modulation schemes when the channel is frequency-selective fading and widely used in current wireless networks. In this thesis work the performance of two pilot-based channel estimation algorithms; namely, least square (LS) and Minimum Mean Square Error (MMSE) with corresponding channel interpolation technique is investigated for digital communication systems. Channel estimation is a technique that can be used to design a channel in a particular surrounding based on known train symbols which is inserted in the input of transmitter end and tested at the receiver end. This thesis performs , analysis of channel estimation algorithms based on bit error rate (BER) and signal to noise ratio (SNR) minimizing the error distance between the transmitted and received data. To estimate the channel coefficients; The MATLAB plot can perform for QAM, 16QAM, and 64QAM constellations. For different international telecommunication union (ITU) channel models Such as, the portable outdoor (PO), portable indoor (PI), Rural Area six path (RA6), Typical Urban six path (TU6), and Rayleigh channel models. Typical urban channel model has better at higher order modulation. From the MATLAB results, LS and MMSE algorithms are compared based on their pilot ratio and channel length. LS estimation has better at high SNR value compared to MMSE estimation.