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Characterization of power system loads in rural Uganda

Uganda is an African country situated in the great lake region. Of its 20 million inhabitants 85% are living in rural areas, less than 1% of them have access to electricity. Different initiatives exist to try to increase the numbers to 10%. To reach this goal and to be able to construct a well functioning electrical grid, load characterization and prediction models are needed. These have to be based on locally collected data that correctly reflect the electrical energy consumption of the targeted area. Therefore field studies have been carried out in rural Uganda in the form of survey-based interviews and measurements. All field work was performed in cooperation with the Uganda Electricity Distribution Company. What should be kept in mind is that the observed area has a slightly higher income than rural settings situated farther away from the main centers. Despite this the results give a picture of the characteristics of the loads in rural households.

The most determining factor for the size of the electrical load is the financial situation of the target area or the individual household. For the households the economical situation will both determine the capacity to buy appliances and the amount of electricity that can be used. The main usage of electricity is for lighting and entertainment in the forms of radio and television. The traditional energy use is instead connected to cooking and is in most cases not affected by electrification. Cooking on electrical cookers is too expensive and many households cannot afford the investment of a cooker (10 to 50 times more than the monthly income). Instead biomass in the form of either charcoal or firewood is still used. So despite the fact that rural electrification is often promoted as a tool against deforestation this can still not be included in one of its advantages. To reduce the usage of firewood and charcoal it is much better to introduce more efficient stoves that are promoted by certain Non Governmental Organizations. Information and education is always an important tool, thus creating awareness about the consequences of the usage of biomass. Viable alternatives must be presented. In the case of the usage of electricity the consumers need to be educated in the connection between the usage of appliances and the costs of electricity, thus avoiding unpleasant surprises when the bill is presented.

Based on the number of appliances, thus indirectly the financial situation, four categories were found. If the area can be considered as “low” the mean of the daily load is around 200 W, if “middle” 280 W, if “middle-high” 400 W, and if “high” 620 W. The average will then be distributed between the different hours of the day. A daily profile shows that power consumption during the day will be very low and rise to peaks during the evening hours and the morning. The main energy consumption (approximately 40% of the daily energy consumption) occurs in the hours between 19:00 and 22:00. A smaller peak occurs even at the morning hours but due to its limitation in time it will influence the total energy consumption less. When planning the expansion of the grid it is important to have a picture of the maximum load that could occur to be able to dimension and plan correctly. In the observed data the peak load is 3.5 times the daily mean and occurs in the evening hours around 20 hours. The morning peak will be closer to 3 times the daily mean.

When a new area needs to be electrified these results can be used to predict the loads based on an estimate of the financial situation and the number of customers. Mean values, energy consumption and peak values can be calculated.

BIOGRAPHY:
Frances Sprei graduated at the beginning of 2003 with a Master in Engineering Physics, at Lund University, Sweden. The studies of engineering have been combined with those of human ecology, in which she holds a bachelor degree.
Her studies included a year at Ecole Centrale, Paris, France. Currently she is working as a teaching assistant at the Department of mathematical statistics at Lund University.
She has been active in student issues both at a local and European level and is now a board member of the Lund Chapter of EWB (Engineers Without Borders) Sweden. Frances is very interested in the role of energy issues in the construction of a sustainable society. This is reflected in her master thesis, a field study carried out in Uganda on rural electrification.