Tanzania Journal of Engineering and Technology

Long-Range Inertia Prediction Considering Contemporary Evolution of Power Grid Networks

Peter Makolo, Francis Mwasilu, Ramon Zamora, Tek-Tjing Lie — Mon, 03 Feb 2025 00:00:00 +0000

Reduced network inertia due to high penetration levels of nonsynchronous generators in modern power systems is becoming a pressing issue. As a result, very quick inertial responses are observed after contingency events in networks. Due to quick inertial responses, there is a practically very limited time interval for control actions in real-time. Thus, system operators need to understand the prior inertia values to plan, control, and operate the network securely. Long-range forecasting of the network's inertia values, in contrast to short-range forecasting techniques, can pinpoint when the network is most likely to be vulnerable in a reasonable time ahead. Thus, in this research work, an improved ARIMA model (i-ARIMA) technique for long-range forecast inertia values in a modern network is proposed. To estimate future inertia values over a long period of time, the i-ARIMA model leverages strong periodic and seasonality characteristics of previous time series data. The i - ARIMAmethod is tuned for optimal values of a moving observant predictor P, periodicity and seasonality factor s and smoothing factor n that give the best forecasts with competitive accuracy. Rigorous evaluation and tests of the method, which are performed on the New Zealand network data using the Power Factory DigSilient platform, demonstrate that the proposed i-ARIMA is quicker, more reliable, more accurate, and better than other conventional forecasting methods.

A Bibliometric Analysis of PAT-SEIG Evolution as an Alternative Energy Generation Method

Emanuel J. Nyirenda, Torbjorn K. Nielsen, Joseph H. Kihedu — Mon, 03 Feb 2025 00:00:00 +0000

Pumps as Turbines (PATs) coupled with Self-Excited Induction Generators (SEIGs) as an alternative energy generation method have been the subject of significant research in recent years. This paper presents a bibliometric analysis of the evolution of PAT-SEIG technology as an alternative energy generation source. An analysis of a comprehensive dataset of peer-reviewed journal articles, conference proceedings, and patents related to PAT-SEIG systems, using advanced bibliometric techniques and PRISMA to identify key research themes, influential authors, the growth of the field and patterns of collaboration, and changes in research focus over time. Over a publication period of 32 years, a total of 949 documents were reviewed using the PRISMA checklist, resulting in the selection of 77 documents for analysis. The findings indicate an increasing interest in PAT-SEIG technology, with an impressive annual growth rate of 9.45%. However, gaps have been identified which provide areas for further studies. These include the PAT prediction methods, voltage and frequency fluctuations
in SEIG, and the overall efficiency of the PAT-SEIG system. The study provides insights into the current state of research and highlights areas
that require further investigation as a way of contributing to the advancement of the technology.

Heavy Metals Pollution in Roadside Ecosystems

Lilian Matafu, Godwill Mrema, Rwaichi J.A. Minja — Mon, 03 Feb 2025 00:00:00 +0000

Heavy metals refer to metallic elements that are characterized by having a relatively high density and they are toxic or poisonous even at low concentration. They are environmental pollutant owing to toxicity and longevity in atmosphere and ability to accumulate in living things via bioaccumulation. They tend to enter in different system such as food chain. Analyses of water, soil sediment and the surrounding growing plants (Cynodon dactylon and Cyperus species) for selected heavy metals (Cd, Pb, Zn and Cu) were conducted on a roadside pond located at Boko MSB, Dar es Salaam. Pond water, soil sediments and plant
samples were collected from Boko MSB site and treated using appropriate methods of acid digestion (aqua regia digestion) involving sample preparation and digestion and analyses for heavy metals and physical-chemical parameters using atomic absorption spectrometry (GBC XPLOOR AAS). Physical-chemical parameters of pond water such as pH, electrical conductivity, total dissolved solids and turbidity were measured. The concentration of Cd and Pb in the water sample were 0.0637 mg/L and 0.995 mg/L, respectively, while the physical-chemical parameters of the pond water indicated a pH of 7.55, electrical
conductivity of 184 µs. Based on the results of the study, the pond water is not safe for potable uses since it contains toxic heavy metals which are above WHO/TBS safe limit. The high concentration of the heavy metals was reflected in both the soil sediments and plants with Cd and Pb in soil samples being above safe limits while Cd, Pb, Zn and Cu in plant samples were also above safe limit.

Review on State of Art of Smoothed Particle Hydrodynamics Method and its Advances in Solid Dynamic

Harold J. Mtyana, Dr. Paul C. Ndumbaro, John K. Makunza — Mon, 03 Feb 2025 00:00:00 +0000

The world is witnessing continued collapse of both buildings and other structures during earthquakes, which is an example of a dynamic effect. One cause of such disasters may be inadequacies of techniques for modeling of these structures during analysis and design as compared to their actual responses during dynamic events. Also, techniques for numerical modeling and analysis of structures in place are meshed methods which do not accurately capture the actual behavior of structural elements especially under high dynamic actions due to the assumption that mesh geometry is unchanged geometry tend to change with respect to time step of such an action. In view of this, meshless techniques such as Smoothed Particles Hydrodynamics (SPH) prove to be promising. However, the application of SPH method especially in solid dynamics, still poses some challenges that reduce its efficiency and need respective improvements. This paper reviews advances so far done in SPH method and its application in solid dynamics with the key focus on weaknesses of the method and soundness of the recommended solutions through reviews from recent research, from which recommendations for further improvements have been presented as
well. Findings from reviewed papers show that efforts towards improving various challenges on the classical SPH specifically on dynamics of solids have been done and are hereby acknowledged. However, critical areas that still pose attention and require further research include criticality on choice of most suitable kernel function that best fulfills all interpolant requirements, criteria for setting of smoothing length and general SPH formulation that appropriately represents dynamic problem of solids other than those which have been covered so far. Special attention on clear way of setting the initial and boundary conditions of the kernel domain is also needed.

Efficient Operation of Direct Coupled Solar Home PV System: A Case of Solar Home PV System Installed in Dodoma, Tanzania

Sarah P. Ayeng’o — Mon, 03 Feb 2025 00:00:00 +0000

Direct coupled Photovoltaic (PV) system is a common topology among most of the off-grid communities in the world. This topology has less components hence resulting in low investment costs. However, it suffers much losses when battery operating voltage is far from maximum power point voltage of PV modules. This scenario can be attributed by different factors such as; variation in solar radiation, load profile and temperature. Efficient operation of these systems is required in order to reduce losses. Usually in direct coupled system, PV modules are connected in parallel with batteries through a charge controller hence making PV output to depend solely on battery operating points. For losses reduction, a proper voltage range of battery and PV modules has to be selected. The challenge to many technicians is on proper selection of ranges of voltages of battery and PV module. This results in installed PV systems being operating away from maximum power point hence much losses. This paper presents a model of solar home PV system developed using MATLAB software. Two types of solar PV modules; A Copper, Indium, Gallium, Selenium (CIGS) thin film and a polycrystalline PV module with 24V lithium nickel cobalt aluminum oxide as a storage were modeled. The Solar radiation data and load profiles were collected from Dodoma, Tanzania. In order to get optimum results, optimization tool was also developed by using genetic algorithm. For efficient operations of direct coupled PV systems, the ratio between 0.7 and 0.9 of battery to PV maximum power point voltages has been proposed. By using these ratios in PV system designing, one can have an assurance of operating PV system at minimum losses in areas with high solar radiation. This can be a simple method to be used when designing solar home system. However, more detailed analysis on battery capacity and PV modules are recommended.

Assessment of Wind Speed Characteristics and Available Wind Power Potential for Electricity Generation in Tanzania

Mwingereza J. Kumwenda, Rajabu J. Mangara — Mon, 03 Feb 2025 00:00:00 +0000

The energy demand and its associated crises are attracting significant attention due to population increase and economic growth especially in developing countries. Fossil fuel-based energy source stand as a prominent anthropogenic resource but they are accompanied with increased carbon emissions and heightened environmental concerns. Renewable energy sources such as wind energy can offers a lot of potential for sustainable growth in the energy sector of developing nations like Tanzania. Thus, this work investigated wind speed characteristics and available wind power potential in six selected regions in Tanzania with different topographical features for future electricity generation. The data of the wind speed of ten years available at a height of 10 m above ground level have been used to analyse monthly and annual variations of wind speed. Minimum and maximum average values of recorded wind speeds are presented in this paper. The Weibull shape k and scale c parameters have been estimated using the Weibull distribution function. Results indicate that the respective maximum average annual values of the shape and scale parameters for all sites are 2.54 and 8.21 m/s, which indicate that the wind speed is steady. The results show further that the Singida region has a maximum average annual wind speed of 7.29 m/s and a corresponding annual average wind power density of 237.30 W/m2 . In conclusion, the results suggest that the Singida region can be considered a suitable site for wind energy generation on a large scale.

Performance Evaluation of Free Space Optical Communication in Dar es Salaam: Impact of Scintillation and Modulation Schemes

Mustafa H. Mohsini, Florence Rashidi, Teck Kinte Chiyaba — Mon, 03 Feb 2025 00:00:00 +0000

Free space optical communication (FSO) holds significant relevance in the modern communication system as it offers high and unlimited data rates, enhanced security, rapid deployment, and low cost for installation. However, the performance of FSO transmission is greatly affected by harsh atmospheric conditions such as wind, temperature, and humidity, which induce scintillation. With the rapid growth of internet users and Dar es Salaam being a business city in Tanzania, higher and unlimited bandwidth for communication is highly demanded. This study primarily aims to evaluate the performance of FSO transmission in Dar es Salaam, Tanzania, by investigating the impact of atmospheric conditions particularly scintillation on link availability and transmission quality. We evaluated link availability and the effect of scintillation in terms of eye diagrams, Bit Error Rate (BER), and two modulation schemes (i.e. Return-to-Zero (RZ) and Non-Return-to-Zero (NRZ) schemes) in the Dar es Salaam region. Our work used weather data, including temperature, relative humidity, and wind speed average data, collected from January 2014 to December 2017 by the Tanzania Meteorological Authority (TMA) in the Dar es Salaam region for link availability and performance analysis. The simulation was performed to determine the FSO link availability, and the scintillation effect was analyzed using the Hufnagel Valley (HV) day prediction model. Results analysis indicates that link availability is significantly influenced by atmospheric conditions, with the simulation results showing that Dar es Salaam has higher FSO attenuation and that the transmission can sustain link availability up to a distance of two kilometers. A comparison of the two modulation schemes has shown that NRZ is the best modulation scheme that could be used, and January is the best month for transmission in Dar es Salaam. This technology is feasible and therefore is recommended for adoption.

Improved Minimum Variance Channel Estimation Techniques for OFDM Systems

Kwame S. Ibwe — Mon, 03 Feb 2025 00:00:00 +0000

Orthogonal frequency division multiplexing (OFDM) systems face challenges in channel estimation due to noise, variability, and the doubly dispersive nature of wireless channels, which degrade performance. To address these challenges, a multichannel minimum variance double dispersive channel estimator is proposed. The method employs a hybrid approach that combines subspace and minimum variance techniques, optimizing the filter bank output power under a signal-to-noise ratio (SNR) constraint. This design preserves the desired signal while effectively suppressing disturbances, achieving robust performance with reduced computational complexity compared to existing methods. Simulation results demonstrate that the proposed estimator outperforms subspace and asymptotic methods in terms of normalized mean square error (NMSE) and bit error rate (BER), particularly under low SNR and frequency-selective conditions. These findings highlight its potential for enhancing spectral efficiency and data integrity in advanced OFDMbased communication systems