The Study Of The Influence Of Nonlinear Load Access To Power Grid And Its Countermeasures

With the development of power electronics technology and industrial technology,more and more semiconductor rectifier and inverter equipment with non-linear load characteristic are widely used,and other non-linear loads(also known as distorting loads)such as: Arc furnace,electric traction locomotives,soft start,switching power supply,UPS,battery charger integrate into the grid,non-linear loads has become an important part of the power system load.According to statistics,30% of non-linear loads is supplied by power electronic device,which resulting in harmonic levels of gird increase year by year.The great harmonic pollution caused harm to the power system,and the voltage fluctuation and flicker caused by AC electric arc furna ces,rolling mills and other large impact load are still trouble.The nonlinear load is mainly caused by the rectifier equipment,electric arc furnace,electric locomotive and rolling mill,which causes the harmonic pollution to the power grid,and affects the power quality and the operation stability of power grid.The three-phase bridge rectifier circuit is studied in this paper,and chlor alkali industry is studied as an example for it's characteristic and structure of load.Then,the chlor alkali plant rectifier load model is established and the simulation,analysis are done.The principle and mathematical model of arc are studied,and the model is built for simulation and analysis.Industrial motor nonlinear load's characteristics are studied,and DC motor load is studied as an example.The theoretical of the harmonics is analyzed,according which,the empirical data of harmonic function is fit and the model is simulated.This paper introduces the regulation of harmonic management of power grid,and the influence of nonlinear load on power system is analyzed,meanwhile,the common countermeasures are studied.simulation model of APF is built according to mathematical model and Parameters of the active filter to be purchased.Then the simulation experiment is carried out with the load data of the Hanshan-Lintou industrial park in Ma'anshan distribution network,and the simulation results show that the harmonics are reduced after the active filter is connected to the grid,which means that the install of APF has a significant effect on improving power quality.