Power Predictive Control Based On Cascaded H-Bridge Active Power Filter

With the development of distributed energy,a large number of power electronic devices are widely used,causing harmonic pollution of the power grid and bringing serious challenges to the power system.Therefore,the research of Active Power Filter(APF)has received extensive attention.This paper takes the single-phase cascade multilevel APF as the research object.Through the analysis of the principle of harmonic generation and the analysis of the detection method,the prediction model of APF is established.The direct power control in the dq coordinate system is realized by using the virtual orthogonal circuit,and the DC side voltage balance is designed to realize the DC side voltage balance Control.The main contents of this paper are as follows:Firstly,the common multilevel topology is analyzed,and the working principle of the cascaded H bridge type single-phase shunt active power filter topology is expounded.The mathematical model of the three-phase stationary coordinate system and the two phase rotating coordinate system is derived.The control method of cascade H type APF based on the predictive direct power control is analyzed.The power and reactive power ratio is the predictive power model of the control object,and the predictive power control algorithm and the instantaneous power theory are used to calculate and compensate the active and reactive power of the harmonic in the line.Secondly,the DC-side voltage equalization strategy of the cascaded APF is studied.The control strategies of several current voltage balance controllers are compared and discussed.These types of control strategies have corrected the active duty cycle,but they have not.Considering the reactive power imbalance under inductive and capacitive load conditions,this paper proposes a voltage balance control strategy that eliminates the coupling between the main circuit controller and the voltage balance controller,and also considers the active and reactive duty cycle corrections.By building a three-module single-phase cascading APF simulation in matlab,the simulation results show that the voltage-sharing control strategy proposed in this paper can effectively balance the DC-side voltage of cascaded APF,and the filtering effect is good.Finally,the APF predictive power control under the two phase stationary coordinate system is studied.In view of the necessity of predicting the power error in direct power control,combined with the characteristic of periodic repetition of the APF input signal,the repetitive control is introduced to optimize the power prediction value,and the APF with no repetitive controller is given by imitation.Compensation performance and instruction tracking performance are compared and analyzed.