Suppression Of Low-frequency Oscillation Of Wind Power System Based On Regional Pole Placement And Optimization Of Damping Controller Parameters

The integration of the doubly-fed induction generator(DFIG)presents new challenge to the research on the low frequency oscillation of the power system because it may influence the damping of interarea mode and introduce new low frequency oscillation modes.Therefore,it is necessary to study the mechanism of the impact that DFIG imposes on the low frequency oscillation of the power system and design the additional damping controller in order to damp the low frequency oscillation modes.The main contents of this paper are as follows:(1)Considering the dynamic interaction between the DFIG and the synchronous generators(SGs),the transfer function of the wind power system is established.The low frequency oscillation mode introduced by the DFIG is extracted based on the detailed dynamic model of DFIG.(2)The analytical expression of the additional torque of the DFIG is newly proposed.Based on its response to the low frequency oscillation mode introduced by the DFIG,the mechanism of the impact that DFIG imposes on the low frequency oscillation of the power system is studied.(3)The dual-input damping controller equipped in combination with the active power control loop of the rotor-side converter of the DFIG is proposed,which can be used to suppress the low frequency oscillation mode introduced by the DFIG and the interarea mode.The parameters of the local control channel are decided by employing the phase compensation method based on the proposed analytical expression of the additional torque of the DFIG The parameters of the wide area control channel are tuned based on the particle swarm optimization considering coordination with the other control channel.(4)The regional pole placement based on the linear matrix inequality is applied to design the output feedback controller.All the weakly damped low frequency modes are placed within the desired region.By calculating the participation factors of the weakly damped low frequency oscillation modes,those highly related generators are determined and equipped with the additional damping controllers to simultaneously suppress all the weakly damped low frequency oscillation modes.