We propose an effective hybrid method, the CSGM, to forecast
electricity consumption in NSW. Based on the inherent
characteristics of GM(1,1), a series of suitable concepts, which
include data selection, an abnormality analysis, a feasibility
test, and optimized algorithms, were used to improve forecasting
accuracy. A case study shows that CSGM performs
better than the classic GM(1,1), the GM(1,1) optimized using
IA and the ARIMAmodel. Finally, we analyzed the forecasting
errors based on statistical theory, which showed that the
ARIMA electricity consumption forecasting model yielded a
significant result with a small average error but with a high
error at certain time-points; thus, ARIMA is not a suitable
consumption forecasting model of electricity consumption in
NSW.