Improved Nonparametric Predictive Current Control For Standalone Brushless Doubly-fed Induction Generators

Brushless doubly fed induction generator(BDFIG)is a new type of AC induction machine.The stator of BDFIG consists of two independent windings with different pole pairs,namely power winding(PW)and control winding(CW).Compared with doubly fed induction generator(DFIG),BDFIG without brush and slip ring has the advantages of long service life,high reliability and low maintenance cost.Bdfig can be used not only for grid connected power generation,but also for standalone power generation,which has a broad application prospect in the field of wind power generation and ship shaft power generation.The main works of this paper include the following aspects:Model predictive current control(MPCC)has attracted much attention due to its intuitive concept and fast dynamic response.However,due to its heavy dependence on the model parameters,the practical application of MPCC in the BDFIG is not satisfactory.In order to overcome this problem,this paper proposes an improved nonparametric predictive current control(NPCC)method,which uses the detected machine information instead of system parameters to predict the current change.Simulation and experimental results show that this method not only keeps the fast dynamic response performance of MPCC,but also is not affected by the change of machine parameters,which means that it is with strong robustness.Firstly,the development history of BDFIG and the research status of its control methods are briefly reviewed.Then,a unified reference frame dq model of BDFIG is introduced,and the relationship between CW current and PW voltage is introduced.Based on this,the basic principle and control method of BDFIG generation voltage amplitude control are introduced..Then,the overall control idea of CW side converter in BDFIG standalone power generation system is introduced,and the basic control method of CW current is introduced.On this basis,the MPC method with faster dynamic response is introduced to replace the current loop in the basic control method.The basic implementation steps of MPC are described,and the discrete mathematical model is derived.Finally,the superiority of MPC is verified in the simulation.Then,aiming at the problem of strong parameter dependence when BDFIG standalone power generation system adopts MPC method,an improved NPCC method is proposed,the mathematical model of the method is derived,and the implementation steps are analyzed in detail.The NPCC simulation model of BDFIG standalone power generation system is built in Simulink,and the good control performance and strong parameter robustness of the NPCC control method proposed in this paper are analyzed and verified.Finally,based on a 5 k VA BDFIG independent power generation system experimental platform,the effectiveness and superiority of the proposed NPCC control method are verified under three different working conditions: constant speed and variable load,constant load and variable speed,and variable motor parameters.