Research On Control Strategy Of Active Power Grid Connected Inverter In Distributed Power System

Due to the rapid development of human society in the past few centuries,as a major energy power in today's society,the demand for daily life and production and quality of electricity requirements are further improved.How to use the new energy,especially the electrical energy,to improve the current energy structure,change the status quo of fossil energy-based energy consumption is a global problem to be solved urgently,the energy crisis ceaseless deepen,environmental pollution ceaseless intensify the environment.For this reason,in order to hydropower,photovoltaic and wind power represented by the new energy power generation technology has been the highest ever concerned with human society.New energy generation technology is mostly used in distributed power generation system,how to build a strong and reliable smart grid is currently a priority issue in the development of power system.Due to the constraints of technology and construction conditions,the distributed power grid based on new energy power generation technology inevitably has the problem of low power quality.The main reason is the harmonics of the pollution of large power grids,harmonics will directly lead to uncontrollable increase of energy loss during the transmission process,resulting in unnecessary energy loss,harmonic flow into the electrical equipment will lead to overheating or even damage to electrical equipment,also because of this reason how to effectively suppress the harmonics in the power system becomes more important in improving the power quality of the power system.In this kind of environment and background,the structure and similarities and differences between the two which of grid connected inverter and active power filter are analyzed in this thesis,with distributed power grid as research premise,research on a new type of inverter with grid connected inverter and active power filter function,namely active filter grid-connected inverter.Active filter type grid-connected inverter is the use of grid-connected inverter capacity to achieve the combination of inverter and active filter function,realize the function of grid side inverter in inverter power supply also both harmonic suppression and reactive power compensation.The new inverter can effectively reduce the system cost,reduce the running cost and reduce the difficulty of maintenance.In this thesis,the mathematical model of the inverter applied in the distributed grid is analyzed theoretically by using the grid-connected inverter which can realize grid-connected inverter and harmonic suppression at the same time.The direct current control strategy as the core,with an improved d qi-i harmonic detection algorithm as the tool are applied to system unified control strategy.The inverter with the unified control strategy can realize the function of the active filter while realizing the function of the grid-connected inverter,and effectively filter the side-side harmonics,which can effectively improve the power quality.Based on the theoretical analysis,the Matlab/Simulink modeling and simulation of the system are carried out.The simulation results show that the active filter-type grid-connected inverter can effectively suppress the harmonics in the power system and complete the work of the grid feasibility and practicability of the system.