Frequency Control And Multi-band Oscillation Suppression Of Power System With Grid-connected Wind Power

Bulk wind power with random output power is intensively integrating into the power grid via power electronic devices.It will cause new oscillation with unknown mechanism and decrease of the system inertia,and profoundly change the characteristics of the power grid.Consequently,the stable characteristics of the power gird become more and more complicated,and the risk of safe and stable operation is significantly increasing.Therefore,in order to ensure safe and stable operation of the power grid and prevent large-scale blackouts,it is urgently necessary to investigate the frequency control and oscillation suppression of power systems integrating bulk wind power.This thesis starts from the basic mathematical model of doubly-fed induction machine based wind turbine(DFIG-WT),after theoretical analysis and simulation research,the control strategy of primary frequency support of the DFIG-WT and the multi-band oscillation suppression of power systems integrating bulk wind power are investigated.The main research content and the progress are listed as follows:1.After briefly reviewing the principles of the DFIG-WT,the mathematical models and control strategies of each part of the DFIG-WT are elaborated.Then,the dynamic simulation model of the DFIG-WT is established in MATLAB/Simulink.Simulation results verify the correctness of the built model,which provides a model basis for subsequent research.2.After analyzing the mechanism of the primary frequency control,a control strategy for the DFIG-WT to participate in the primary frequency control of the system is proposed.This strategy adds control signal based on tie-line power deviation to the rotor side converter control loop of the DFIG-WT.It can effectively improve the primary frequency modulation capability of the DFIG-WT.On this basis,an active power distribution method based on the consensus algorithm and a multi-band oscillation damping controller based on the residue method are proposed for DFIG-WT.Simulation results based on the 16-machines 68-bus system verify the effectiveness of the proposed coordinated control strategy and multi-band oscillation damping controller.3.To suppress the low-frequency oscillation and the sub-synchronous oscillation existing in power systems integrating bulk wind power more effectively,an adaptive compass search based optimized design method for multi-band oscillation damping controller is proposed.The proposed multi-band oscillation damping controllers act on the rotor side control loop of the DFIG-WT,which can effectively suppress the multi-band oscillations in the power systems integrating bulk wind power.Simulation results of the 16-machines 68-bus system verify the effectiveness of the proposed multi-band oscillation damping controller.