An Improved Nonhomogeneous Discrete Grey Model and Its Application

Table 2

The results of five grey models in wind turbine capacity of Europe (megawatts).

Year	Raw data
				2007		56748.89
		2008	64943.48	68733.07	68819.11	68053.13	62092.57	64959.03
		2009	77019.99	76808.49	76910.91	76293.36	72082.88	76284.64
		2010	86721.97	85832.70	85954.16	85366.11	82532.46	86889.65
2011	96603.13	95917.15	96060.72	95432.01	93462.41	97623.26
2012	109884.87	107186.43	107355.62	106629.26	104894.83	108856.78
2013	120994.68	119779.73	119978.58	119099.88	116852.81	120818.76
2014	133915.44	133852.61	134085.77	132997.36	129360.50	133684.27
2015	147637.65	149578.91	149851.68	148490.51	142443.19	147607.95
RMSE		1877.41	1880.05	1909.43	4325.85	586.52
MAPE (%)		1.58	1.54	1.79	4.22	0.44
2016	161939.87	167152.88	167471.36	165766.36	156127.30	162739.02
2017	178314.15	186791.62	187162.78	185032.76	170440.49	179229.35
RMSE		7037.15	7378.88	5467.26	6920.28	859.14
MAPE (%)		3.99	4.19	3.07	4.00	0.50