2009, Da Silva, I. P., Demetri, I., De Silos, A. C., Brandao, F. A (Jr), Da Silva, Izael

The accuracy class of an IVT – Inductive Voltage Transformer – is typically assessed in laboratory installations either by comparing with another IVT presenting greater accuracy and traceable to a national laboratory or by using a capacitive divider. Calibration in the field is considered herein, using results obtained from typical open and short circuit tests and winding resistances, performed with common meters. A Möllinger & Gewecke graphic diagram is employed together with the results of an accuracy test previously carried out to determine the exact value of the winding turn relation and of the primary winding dispersion reactance. These values are used to calculate the phase and ratio errors, which must lie between definite limits, defined by the accuracy class of the instrument. Four commercial IVTs were tested to determine the validity of the procedure. The errors are compared with those obtained with the Schering-Alberti method (AC Bridge and comparison with standard IVT)

2007-07-20, Sendegeya, A., Amelin, M., Soder, L., Lugujjo, E., Da Silva, I. P., Da Silva, Izael

This paper presents a methodology using Monte Carlo Simulation for analysing and compare the impact of two types of monopolistic rural power system operators (altruistic and profit maximising operators) on the probability distribution of tariff levels and reliability of the system. The market has price sensitive consumers. The developed model has been demonstrated on two power systems: only diesel genset and a wind-diesel hybrid system showing the impact of the generation costs and capacity of generation from wind on the tariff levels, expected profit and reliability.

2007, DaSilva, Izael, Buchholz, Thomas, Tennigkeit, Timm, Timothy A., Volk, Da Silva, Izael

Uganda currently faces an electricity crisis due to high fossil fuel prices and falling levels of lake Victoria affecting hydro power capacities. In this paper, we introduce a feasibility study for a 50 MW biomass fired power plant covering plantation design, conversion technology, environmental and social impacts, anticipated problems, overall economics, project status, and benefits of the project. The 30,000 ha project area consists mainly of Eucalyptus and native Markhamia lutea stands. Results indicate that this project can provide electricity to a competitive price which is considerably lower than generated by fossil fuel powered generators.

1999-08-27, Brandao, A.F., de Silos, A.C., Ivanoff, D., da Silva, I.P., Da Silva, Izael

It is shown here that the precision class of an IVT-inductive voltage transformer-can be verified in the field, using the results obtained in the usual tests of no-load loss and current, short circuit and winding ohmic resistances, performed with common meters. A graphic diagram-the Mollinger and Gewecke diagram-is employed together with the results of an accuracy test previously carried out in order to determine the exact value of the winding turns relation and of the primary winding dispersion reactance. These values are used to calculate phase and magnitude errors, that must obey standards and must lie between definite limits, defined by the precision class of the instrument. Some commercial IVTs were tested in order to check the validation of the procedure. The errors were compared with the ones obtained with the Shering-Alberti method (CA bridge and comparison with standard IVT).

2007-01, Da Silva, I. P., Buchholz, T., Volk, T, Tennigkeit, T, Da Silva, Izael

Small-scale wood gasification systems have the potential to contribute to the rural electrification in Uganda. This paper presents an economic analysis of a 10 kW gasifier unit and its minigrid installed on a Ugandan farm. The bioenergy system has been running stable on a six hour daily base for seven months. When the gasifier is operated close to the rated capacity, the gasifier system is economically attractive compared to diesel generated electricity Results indicate that replicating successful wood gasification systems stipulates integration of sustainable fuelwood supply and viable business models.

2009-08, Bakkabulindi, G., Da Silva, I. P., Lugujjo, E., Da Silva, Izael

The 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.