Browsing by Author "Bakkabulindi, Geofrey"
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Item Energy Storage Options for Environment Monitoring Wireless Sensor Networks in Rural Africa(Springer, 2012) Byamukama, Maximus; Akol, Roseline; Bakkabulindi, Geofrey; Pehrson, Björn; Olsson, Robert; Sansa-Otim, JulianneThis paper explores various traditional and emerging battery technologies available for deployments of automated environment monitoring devices using Wireless Sensor Networks (WSNs) in Africa and the considerations designers must take into account when implementing these systems. Environment-monitoring applications of WSNs are focusing more on reducing power consumption and optimizing data transmission and less on the constraints that their applications and deployment environments put on the energy storage device. We describe the various properties of energy storage devices and, for each, we highlight the requirements to be met for environment monitoring applications, especially in remote areas in Africa. We evaluate the performance of some of these energy storage options against the requirements using three use cases. We indicate the technologies that have shown reliability for each use case. We show that emerging battery technologies, such as Lithium Ion Capacitors are well suited for long-life low power deployments while the options for high-power deployments depend on the constraints faced by the designers, such as the power consumption of the sensor network components sand environment temperature range of the deployment environment.Item A Heuristic Model for Planning of Single Wire Earth Return Power Distribution Systems(Bakkabulindi, G., Hesamzadeh, M. R., Amelin, M., Da Silva, I. P., & Lugujjo, E. (2011)., 2011) Bakkabulindi, Geofrey; Hesamzadeh2, Mohammad R.; Amelin, Mikael; Silva, Izael P. Da; Lugujjo, EriabuThe planning of distribution networks with earth return is highly dependent on the ground’s electrical properties. This study incorporates a load flow algorithm for Single Wire Earth Return (SWER) networks into the planning of such systems. The earth’s variable conductive properties are modelled into the load flow algorithm and the model considers load growth over different time periods. It includes optimal conductor selection for the SWER system and can also be used to forecast when an initially selected conductor will need to be upgraded. The planning procedure is based on indices derived through an iterative heuristic process that aims to minimise losses and investment costs subject to load flow constraints. A case study in Uganda is used to test the model’s practical application.Item New Techniques for Sizing Solar Photovoltaic Panels for Environment Monitoring Sensor Nodes(Journal of Sensors, 2019) Byamukama, Maximus; Bakkabulindi, Geofrey; Akol, Roseline; Sansa-Otim, JulianneThe development of perpetually powered sensor networks for environment monitoring to avoid periodic battery replacement and to ensure the network never goes offline due to power is one of the primary goals in sensor network design. In many environment-monitoring applications, the sensor network is internet-connected, making the energy budget high because data must be transmitted regularly to a server through an uplink device. Determining the optimal solar panel size that will deliver sufficient energy to the sensor network in a given period is therefore of primary importance. The traditional technique of sizing solar photovoltaic (PV) panels is based on balancing the solar panel power rating and expected hours of radiation in a given area with the load wattage and hours of use. However, factors like the azimuth and tilt angles of alignment, operating temperature, dust accumulation, intermittent sunshine and seasonal effects influencing the duration of maximum radiation in a day all reduce the expected power output and cause this technique to greatly underestimate the required solar panel size.Themajority of these factors are outside the scope of human control and must be therefore be budgeted for using an error factor. Determining of the magnitude of the error factor to use is crucial to prevent not only undersizing the panel, but also to prevent oversizing which will increase the cost of operationalizing the sensor network. But modeling error factors when there are many parameters to consider is not trivial. Equally importantly, the concept of microclimate may cause any two nodes of similar specifications to have very different power performance when located in the same climatological zone. There is then a need to change the solar panel sizing philosophy for these systems. This paper proposed the use of actual observed solar radiation and battery state of charge data in a realistic WSNbased automatic weather station in an outdoor uncontrolled environment.We then develop two mathematical models that can be used to determine the required minimum solar PV wattage that will ensure that the battery stays above a given threshold given the weather patterns of the area. The predicted and observed battery state of charge values have correlations of 0.844 and 0.935 and exhibit Root Mean Square Errors of 9.2% and 1.7% for the discrete calculus model and the transfer function estimation (TFE) model respectively. The results show that the models perform very well in state of charge prediction and subsequent determination of ideal solar panel rating for sensor networks used in environment monitoring applications.Item Rural Electrification Practicalities of Using Single Wire Earth Return as a Low-Cost Method for Grid Extension: The Case of Ntenjeru, Uganda(Bakkabulindi, G., Da Silva, I. P., & Lugujjo, E. (2009, August), 2009) Bakkabulindi, Geofrey; Silva, Izael P. Da; Lugujjo, Eriabu; Söder, Lennart; Amelin, MikaelThe fact that the vast majority of Uganda’s rural areas remain un-electrified makes it imperative that low cost distribution technologies be implemented in order to provide affordable electricity to rural households. Such low cost technologies include the Shield Wire System (SWS), Single Wire Earth Return (SWER) and appropriate engineering techniques. The SWER technology is presented in this paper as well as the implications of its proposed implementation for electrification of the village of Ntenjeru in Uganda. While SWER can reduce the costs of electrification by more than a third compared to conventional high tension transmission lines, there are stringent grounding and safety issues as well as load capacity constraints involved. Furthermore, with the earth used as a current return path, soil resistivity analysis is important in these systems. Since soil resistivity can vary sharply over varying terrain and in different weather conditions, robust SWER systems have to be carefully designed. An analysis of the financial and electrical load implications of this technology in Uganda’s local conditions will be presented and its viability as a sustainable method for electric energy distribution in the chosen case study area.Item Technical, Economic And Sustainability Considerations Of A Solar Pv Mini Grid As A Tool For Rural Electrification In Uganda(Bakkabulindi, G., Sendegeya, A., Da Silva, I., & Lugujjo, E. (2010, July), 2010) Bakkabulindi, Geofrey; Sendegeya, Al-Mas; Silva, Izael Da; Lugujjo, EriabuThe challenges facing rural electrification in Uganda are diverse with less than 3% of the rural population having access to electricity. The establishment of mini-grids powered by renewable energy sources makes it possible to electrify remote areas at affordable rates. In this study, an assessment of a solar PV mini-grid system to provide electricity to forty households in rural Uganda was carried out. The considered system comprised six solar modules each rated 175 Wp, a controller, off-grid inverter and batteries with a capacity of 600 Ah. Manufactured by SMA, the Sunny Island inverter proposed for the mini-grid would ensure provision of grid-quality electricity. The study aimed to investigate the mini-grid’s technical design with focus on optimal distribution against constraints of voltage drops, electrical losses and increasing load. Customised load limiters shared between households using thermistors were included to reduce costs and limit consumption. The incomes of rural households are often seasonal and thus issues pertaining to affordability and sustainability were also considered. Results of the economic analysis showed a payback period of less than 5 years given an affordable fixed monthly tariff for the case study area.