###### Abstract
Therefore, it is very necessary to estimate the influence of the BCS on dynamic response and fatigue characteristics of modern wind turbines. During the last two or three decades, a number of approaches have been investigated to simulate the dynamic characteristics of wind turbine subjected to external loads. [PERSON] [4] derived the local loads of inertia and presented a wind turbine model to simulate the dynamic characteristics. [PERSON] [5] studied the aerodynamic characteristics of blades by simplifying blades to cantilever beams. For an elastic wind turbine blade, [PERSON] [6] presented a mathematical model by combining finite elements and virtual work. [PERSON] et al. [7] utilized an FEM model studying the dynamic characteristics of wind turbine under the excitation of earthquake and wind loads. [PERSON] et al. [8] associated the coupling of the tower/nacelle with the blade motion and found that the blade-tower interaction could lead to the blade tip response increase. [PERSON] [9] developed a detailed model for a rotor blade including the effects of gravity, pitch, and rotor speeds. [PERSON] et al. [10] studied the coupling of blade and tower with a dynamic FEM to obtain response characteristics of a wind turbine subjected to wind load more accurately. [PERSON] et al. [11] analyzed the dynamic response of a tower using the finite element method. To compute the non-linear aeroelasticity of wind turbine, [PERSON] and [PERSON] [12] presented an aeroelastic model. [PERSON] et al. [13] developed an integrated finite element model of a 5-MW wind turbine and studied the impact and mechanism of the dynamic interaction with considering the mechanical energy distribution during dynamic response. [PERSON] et al. [14] considered the blade-tower aerodynamic coupling, he used CFD and coupled model to predict the aerodynamic loads acting on the tower due to the vortex shedding from the front blades. [PERSON] et al. [15] developed and verified a generalized analytical model allowing to efficiently estimate wind turbine tower displacements under a variety of flow conditions. [PERSON] et al. [16] studied the dynamic response of tall offshore monopile steel wind turbine towers under wind, wave, and current through experiment. [PERSON] et al. [17] investigated the dynamic response of a 5-MW offshore wind turbine with monopile foundation subjected to wind and wave actions by modeling a tower as a multi-degree of freedom system. It is worth noting that few researchers took the variation of blade-pitch angle or/and rotor speed into account when analyzing the dynamic response of wind turbine. [PERSON] and [PERSON] [18] studied the tower displacements of wind turbines with different design load cases including different sources of nonlinearities, but they did not consider that the blade-pitch angle and rotor speed will change along different wind speeds during normal operation with BCS working. [PERSON] et al. [19] used a method named analytical transfer matrix method (TMM) studied the dynamic response of wind turbine towers and the results were compared with FEM. However, the FEM cannot consider the effect of control system on support structure dynamic responses and they also ignored the control system. In a turbulent wind field, although [PERSON] et al. [20] investigated the aerodynamic interaction of a rotating blade, the blade-pitch angle and rotor speed were still constant during one simulation in time domain. In fact, for modern wind turbines during normal operation, the blade-pitch angle and/or rotor speed are not always constant, which are regulated according to the BCS. Therefore, more reasonable results of wind-induced response can be obtained when the BCS is considered. During the whole lifetime, the wind turbine tower and blades experiences fatigue loads caused by fluctuating wind conditions, which may cause damage failure. In most cases, wind turbine is in the state of running to obtain energy from atmosphere with the power control system working.