The Study On The Series Power Optimizer Of PV Grid-connected System

The distributed generation system is equipped with the special maximum power point tracking module for each photovoltaic cell.Each photovoltaic cell can output its maximum power in the process of generating electricity.The distributed generation system can greatly improve the power generation efficiency of the system,therefore,it has received extensive attention in recent years.As a component level maximum power point tracking module,photovoltaic power optimizer has become a hot research topic in photovoltaic industry for its both advantages of low cost and high efficiency.First of all,the principle of photovoltaic cell power generation was elaborated in detail in this article.And I obtained the equivalent model of photovoltaic cell based on this principle,and according to the equivalent model,the simulation model of photovoltaic cell has been built in Simulink,so I got the output characteristic of photovoltaic cell with the simulation result.Further more,the photovoltaic array was simulated,and the multi peak output characteristics of the PV array were obtained.Then,the MPPT principle of photovoltaic cells is discussed in detail,and combined with the output characteristics of PV cells,I analyzed the principles and advantages and disadvantages of several commonly used MPPT algorithms.The Simulink modeling and simulation verification of fuzzy control method and P&O method were carried out.Combining the advantages of the two algorithms,I designed a combinatorial control MPPT algorithm which was based on the two algorithms.The combinatorial algorithm was modeled and simulated by Simulink,and the simulation results verified that the combinatorial algorithm ensured good dynamic response speed and steady state accuracy.Finally,I analyzed and determined the design of the hardware and software of the power optimizer.The experimental platform was set up to test the prototype of the power optimizer.The test Included power optimizer working efficiency test,MPPT efficiency test,series connection test and communication function test.The test result showed that the communication function is good,and both the efficiency of the power optimizer and the MPPT efficiency meet the expected requirements.Also the test result proved the correctness and feasibility of the hardware and software design scheme of the power optimizer in this article.