Research On Key Technologies Of Double Resonant Active Power Filter

With the rapid development of power electronics technology,the application of power electronic equipment has improved the utilization rate of electric energy and improved people's living standards,but it also brought harmonic pollution problems to the power grid.Active Power Filter(APF)is widely used because it is a device that can effectively control harmonics.This paper presents a new double resonance type three-phase active power filter(DRAPF)topology against the problems with traditional APF,which can not only effectively reduce the capacity of the active side,reduce the fundamental current of the active side,but also reduce the operating voltage of the inverter power device.The mathematical model,harmonic suppression method,main circuit parameter calculation and control algorithm of DRAPF topology are analyzed and studied.Its feasibility is verified under simulation and experiment.Firstly,this paper introduces the methods of harmonic generation,hazard and harmonic control,and then analyzes the current research status of APF topology,harmonic extraction strategy and harmonic control strategy.Secondly,the mathematical model of DRAPF in abc static coordinate system and dq rotating coordinate system is given,and the structural block diagram of the control object is established.Based on the analysis of mathematical models,the design method of DRAPF main circuit parameters is discussed.Then according to the DRAPF topology and the main circuit parameters,the harmonic suppression function of the topology is given.Furthermore,the effects of DRAPF on the grid side equivalent impedance change,resonance detuning and parallel resonance resonance capacitance and inductance parameters are discussed.Again,this paper designs the DRAPF control system.The harmonic extraction strategy,low-pass filter design and passive damping resistance selection method in synchronous rotating coordinate system are analyzed.According to the characteristics of high-order model of DRAPF topology,the dominant pole method is used to reduce the order of the system model,and the simplified equivalent model is used to adjust the controller parameters to complete the controller design.Finally,TMS320F28035 was chosen as the microprocessor of this article and builds the experimental platform of DRAPF system.It introduces the framework of the hardware platform of the system and the circuit of each part.The design method of the main program,ADC interrupt subroutine and timer interrupt subroutine in the system is given.The validity of the proposed topology and control algorithm is verified on the experimental platform.The experimental results show that the DRAPF has good specific subharmonic suppression capability and small capacity.