Research On Model Predictive Control Of Active Power Filter Based On Deadbeat Control

Active power filter(APF)is considered as an ideal equipment to improve power quality,and it has been applied in practice.Shunt APF not only can suppress harmonics and compensate reactive power at the same time,improve the power factor,but also effectively avoid the resonance in the process.However,due to the delay caused by digital control,it has gradually become the main factor affecting the effect of APF.Considering the above problems,this thesis studies the time delay caused by digital control,adopting three-phase three-wire system parallel topology structure.In this paper,the classification and topology of active power filter is firstly introduced,its working principle is analyzed and its mathematical model is formed.Aiming at the problem of the time delay,a model predictive control based on deadbeat control is proposed.Firstly,the predictive command current with no actual error is obtained by using the deadbeat control.Then,according to the actual command current,the predicted command current and the voltage signal,the value function are established.After that,the voltage vector is obtained by rolling optimization process to obtain the minimum value of the value function.Finally,according to the pre-established prediction model to find the switch state which matches the minimum voltage vector,and the state is the optimal switch state,and then output the PWM signal.In this paper,the control method of APF system is based on current control strategy,whole system adopts double closed-loop controllers,which respectively are the DC bus voltage control loop and harmonic and reactive current tracking control loop.The ip-iq method which is based on the instantaneous reactive power theory is used to detect harmonic and reactive current.A model predictive control based on deadbeat control is used to achieve the command current tracking control to generate the main-circuit control PWM signal.The control method of APF system is simulated in MATLAB/Simulink,the simulation results show that after compensating,the current distortion rate is only 3.19%,and the power factor is approximately equal to one,so the proposed control method can control APF realize harmonic and reactive power comprehensive management,and has good dynamic characteristics.Finally,the APF experimental platform is built in the lab environment.The experimental results show that the model predictive control based on deadbeat control can effectively suppress the harmonic and compensate the reactive power and has good dynamic performance.