MPC control of robust type DFIG on multi-parameter mismatch
The model predictive current control(MPCC)is based on the system model in DFIG,which has the problem of poor robustness of system parameters.In this paper,a sliding mode observer(SMO)combined with MPCC control strategy based on new sliding mode reaching law(NSMRL)is proposed.At first,the mathematical model of DFIG by voltage orientation is established.Then,the model of the deadbeat control system is established.Finally,An improved sliding mode reaching rate of isometric extension term and exponential arrival term is constructed,NSMRL includes the system state variable and the power term of the sliding mode surface function,and can represent the approach law in two different forms.The function of the new sliding mode approach rate is to make the system state converge to the sliding mode plane faster and with less buffeting,thus improving the parameter robustness.The results show that proposed method can suppress the inherent chattering of the system effectively and can also increase the speed of the system state reaches the sliding mode surface compared to that of the MPCC without sliding mode and MPCC with constant velocity approach rate methods.Specifically,the average torque ripple,current ripple and phase current THD can be reduced by 10.54%,24.16%and 5.12%,respectively.Therefore,the NSMRL-SMO-MPCC control strategy proposed in this paper can predict the current more reliable by compensating the disturbance online to improve the parameter robustness of the system while the parameters are mismatched.
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