Research On Distributed Power Combination Photovoltaic Grid-connected System

With the advancement and development of photovoltaic technology,the stability and conversion efficiency of photovoltaic systems have been greatly improved.However,there are still low conversion efficiency uder low load or shade conditions and poor grid-connected power quality in photovoltaic grid-connected.problem.This paper introduces the idea of micro-energy network in photovoltaic grid-connected system,and proposes to adopt a distributed power combination method to form multiple photovoltaic strings into a multi-energy network,and to DC/DC converters and DC/AC in the system.The module performs coordinated optimization control.In this paper,the output characteristics of photovoltaic modules are engineered from the principle of photovoltaic cells.A new algorithm of variable step size maximum power tracking(MPPT)is studied for its PV curve characteristics,and the boost circuit model will be built.It is compared with the traditional algorithm.Secondly,the system adopts multiple low-power inverter parallel structures,and adopts group control strategy for multiple inverters to reduce power loss due to weak illumination.Then,the small power combined inverter system and the corresponding group control strategy were developed,including the common DC 2bus structure of the group control technology and the DC switch cabinet,and an improved equal power operation methocd was proposecd.Finally,through the power generation and power quality test in low-power environment,it is proved that the system can effectively improve the conversion efficiency of photovoltaic system in low-power environment,and the power quality is at a high level.The research and developrment of this paper also proves that it has certain engineering application and promotion value in the application of related engineering.