Research On Control Strategy For Shunt Active Power Filter System With Grid-connect Photovoltaic Power Function

In the current background of global energy such as oil and coal’s shortages,solar energy as an inexhaustible,green energy gradually become the main research subject of new energy.Solar photovoltaic power with high quality and short construction period is safe,reliable and noiseless.But as limited by photovoltaic conversion’s low efficiency,high cost and strict requirement of photovoltaic grid-connected system,solar power still didn’t reach practical level.Due to the switch of power electronic device,photoelectric conversion often injects a large number of harmonic component to the grid,thus affect the voltage and current waveforms in ac power grid. Photovoltaic power generation and shunt active power filter are effective ways to solve the above-mentioned problems.Photovoltaic power generation and shunt active power filter also face some problems in practical application.Photovoltaic power generation can only work during the day,and must be cut away from grid at night, such frequent cutting action will then reduce the utilization of equipment and affect the stability of grid.Moreover,the input cost of practical application is high, which is unfavorable in industrialization development. As the working principle of photovoltaic power generation and shunt active power filter is different, study on their structural topology and control strategy showed that photovoltaic power generation function of Shunt Active Power Filter (PVPC) can achieve photovoltaic power generation and improve power quality without increasing the cost of the overall system hardware conditions, it can achieve photovoltaic power generation and improve power quality without increasing system’s hardware.In addition, by combined photovoltaic power generation and shunt active power filter filter into a set of device with multi-function, can not only improve the utilization of resources, reduce the cost, but also improve the utilization of system.This article analysis and study the PVPC system’s control strategy,puts forward that: in harmonics detection part,using dustpan-shaped variable step size LMS harmonic detection method for synthesizing photovoltaic grid merge command signal and harmonic signal detection is beneficial to the detection accuracy;in current tracking control part, using chaotic binary particle swarm optimization algorithm to predicted the next moment and net current value can improve system’s response speed;in command current tracking control system, using generalized PI control loop embedded in fast repetitive control dual composite control can enhance the capacity of system’s response;in photovoltaic conversion part, using variable step size based on disturbance observer method of the PV module maximum power point tracking can Improve the processing rapidity and stability of system.The paper constructs the mathematic model of PVPC by using simulink block of MATLAB7.0.The analysis of the output waveform compensation,shows that such control system can achieve photovoltaic power generation and improve power quality simultaneously.Also,the current distortion rate is below 5%, meet the requirements of national standards,which indicate the feasibility of this system again.