Research Of Hybrid Switching Control For Photovoltaic Generation Wide-input Series-parallel Grid-connected Interface

With the problems of energy crisis and environmental pollution becoming serious increasingly,it has been the inevitable trend that developing and utilizing vigorously clean and renewable energy in today's world.As a kind of inexhaustible and renewable energy,solar energy will become one of the world's dominant energy in the future.Grid-connected photovoltaic power generation is one of the main ways to utilize solar energy effectively.But influenced by environmental factors such as illumination and temperature,photovoltaic power output has typical randomness and intermittent characteristics,thus the problems such as poor power quality and low generating efficiency must be caused inevitably when photovoltaic power generation connected to the grid.Thus,the grid-connected interface which connecting the photovoltaic power generation system with the power grid was mainly researched in this paper and it has important theoretical significance and practical value to research it's main circuit topology structure and control method.For the actual output characteristics of photovoltaic power generation,a single-stage photovoltaic generation wide input series-parallel grid-connected interface was proposed which can change the topology operation mode timely according to the change of output voltage of photovoltaic power generation to broaden the power range and improve the generating efficiency of photovoltaic grid-connected system,and can also improve the voltage and current power quality of the power grid.Firstly,the main circuit topology structure and working principle of photovoltaic generation wide input series-parallel grid-connected interface were introduced in detail,and the hybrid switching features of photovoltaic generation wide input series-parallel grid-connected interface was mainly analyzed from two aspects of operation mode and switch state transform.Combining the continuous sate equations of work modal and the switching rules between the working modal,the hybrid switching system model of photovoltaic generation wide input series-parallel grid-connected interface was established.Secondly,the event-driven hybrid switching controller was designed by using hybrid switching control theory according to the three-level switching control principle of photovoltaic generation wide input series-parallel grid-connected interface.A simulation model of photovoltaic generation grid-connected system was established on the Matlab/Simulink/Stateflow platform,and the validity and feasibility of grid-connected interface topology structure and control method presented in this paper were verified by the simulation results.Finally,the control system of photovoltaic generation wide input series-parallel grid-connected interface based on the technology of DSP was designed.Photovoltaic generation wide input series-parallel grid-connected interface researched in this paper can adapt to a wide range of input voltage and improve the voltage and current power quality of the power grid,with the friendly operation between the photovoltaic generation and the power grid,which is a power electronic grid-connected interface with high efficiency and performance.By the hybrid switching features of photovoltaic generation wide input series-parallel grid-connected interface,applying hybrid switching control method theory to the photovoltaic generation grid-connected system can describe clearly the continuation character,discrete character and interaction with each other of the photovoltaic generation grid-connected system,and is conducive to solve present problems in the control of photovoltaic generation grid-connected.Thus,the research content possess a certain theoretical significance and practical value.