Monopile Foundation Stiffness Estimation of an Instrumented Offshore Wind Turbine through Model Updating

Table 8

Comparison of averages over all idling datasets between identified and rigid-rotor FE predicted modal behaviour, using foundation design model and model updating estimate parameters. _data, average field data identified frequencies; _avg, average FE model predicted frequencies; , average absolute frequency prediction percentage error; , variance of absolute frequency prediction percentage error; , average MAC; , average S2MAC.

		Tower dominated mode
		1^st FA	1^st SS	2^nd FA	2^nd SS	3^rd FA	3^rd SS
Data	data	0.988	1.000	4.044	4.175	9.842	11.187
PISA	avg	0.990	0.996	4.057	4.218	8.786	11.385
		0.54%	0.49%	0.53%	1.07%	10.44%	1.83%
		0.64%	0.44%	0.54%	0.52%	0.70%	0.69%
		0.811	0.920	0.884	0.918	0.953	0.961
		0.998	0.998
API/DNVGL	avg	0.957	0.962	3.706	3.829	8.468	10.743
		3.13%	3.76%	8.27%	8.27%	13.68%	3.92%
		0.62%	0.43%	0.49%	0.47%	0.67%	0.67%
		0.811	0.920	0.874	0.904	0.968	0.951
		0.998	0.998
API/DNVGL -Kallehave	avg	0.972	0.978	3.888	4.031	8.652	11.124
		1.55%	2.16%	3.75%	3.42%	11.81%	0.69%
		0.63%	0.43%	0.52%	0.49%	0.68%	0.68%
		0.811	0.920	0.880	0.912	0.969	0.958
		0.998	0.998
Ensemble model updated,	avg	0.991	0.998	4.018	4.172	8.700	11.182
		0.59%	0.41%	0.64%	0.43%	11.32%	0.57%
		0.64%	0.44%	0.54%	0.51%	0.69%	0.68%
		0.811	0.920	0.883	0.917	0.965	0.959
		0.998	0.998