CASE STUDIES
The ANN approach described in the previous section was used to forecast hourly load values for
a Brazilian electric company (CEMIG - State of Minas Gerais). The test period covers a whole year
(from March/1993 to February/1994).
The forecasting performance is analyzed through 3 metrics:
* Mean Absolute Percentage Error (MAPE).
* Root Mean Squared Error (RMSE).
* Theil's U (U).
approach to be tried in the fume is to use a specific network to handle only Holidays.
Table 1 Forecasting Error for each Month To analyze the forecasting performance in detail,
we consider two particular months: March and August.
Table 2 shows the MAPE, RMSE and Theil's U for each day of these 2 months and
Table 3 shows the MAPE obtained for each particular forecasting hour (forecasting with leading times up to 24 hours).
As shown in Table 2, the MAPE is below 2% for almost all days in both months. Also, the U coefficient is below 1
for all days, showing the ANN really extracted the more relevant information of the load series in the training
process.
MAPE and RMSE have been commonly used to evaluate forecasting performance; addtionally, we use a metric called
Theil'r; U, which is the rate between the RMSE of the actual forecasting system (the ANN) and the RMSE of a "naive"
forecasting system