Research On Feeder Power Flow Control Method For Impact Load

With the continuous development of my country’s manufacturing industry,there are more and more impulsive loads in the low-voltage distribution network of industrial enterprises,which not only causes power quality problems such as voltage fluctuations,but also increases the power loss of the grid,which is not conducive to the goals of energy saving and emission reduction achieve.At present,SVG and APF,which are widely used in low-voltage power grids,can well compensate load reactive power and harmonics including reactive power impulse.This article will further study the combination of low-voltage feeder reactive power compensation,harmonic compensation and active power on this basis.Active feeder power flow controller with power shock compensation.Aiming at the three-phase four-wire connection mode of low-voltage distribution network,the active feeder power flow controller adopts three-phase four-leg voltage source converter as the main circuit topology,and adopts parallel connection of super capacitors on the DC side as a smoothing method for active power impact.The working principle of the power flow controller and the compensation principle of the impact load are discussed,the mathematical model of the power flow controller is established,the main circuit parameters of the power flow controller are designed,and the load impact characteristics and the DC voltage fluctuation requirements of the converter are combined to improve The parameter selection method of super capacitor.The detection method of impulse compensation current is studied.Using instantaneous reactive power theory and moving average filter,the load current is decomposed into fundamental active power stable components,fundamental active power fluctuation components,harmonic active components,fundamental reactive power components and harmonic reactive components,and fundamental active power is eliminated.In addition to the stable component,the remaining components are then combined to form a three-phase current compensation component.Aiming at the DC voltage fluctuations caused by impulsive power compensation when supercapacitors are used as DC voltage support capacitors,a DC voltage upper and lower limit protection strategy is designed to ensure the normal compensation of reactive power and harmonics for DC voltage when the load is too large.The model predictive current control strategy of the power flow controller is studied,and the rapid compensation of load reactive power,harmonics and active power impact is realized.The simulation verifies the correctness and effectiveness of the control strategy.Based on the PLECS real-time simulation platform,an active feeder power flow controller experimental system with a capacity of 30kVA has been established.The experimental results show that the active feeder power flow controller designed in this paper dynamically compensates for load reactive power and harmonics at the same time.It can well compensate the load active power impact and achieve the purpose of smoothing the impact load power.