Study On Voltage Stability And Voltage Regulation Strategy Of Grid-connected Photovoltaic Power System

With the increasingly prominent environmental and energy issues,photovoltaic power generation is recognized as one of the most promising new energy technologies.As the penetration of photovoltaics in the power grid increases,the influence of photovoltaic installations on the grid voltage will become more and more significant.Therefore,it is of great theoretical importance and pragmatic value to study the grid connection performance of photovoltaic systems to make photovoltaic power supply and grid operate more friendly and coordinated.Firstly,the design principle of the photovoltaic grid connected system was analyzed in detail,and the mathematical model of the grid connected inverter topology circuit was derived.The PQ control principle,as well as the structure and control principle of the DC/DC converter,were analyzed.The external characteristics of the photovoltaic cell were simulated and analyzed using the PSCAD/EMTDC simulation platform.Secondly,the impact of photovoltaic power generation on the steady-state voltage distribution of the distribution network was studied.Based on the structural characteristics of the distribution network after the integration of photovoltaic power sources,a detailed study was conducted on the changes in the voltage distribution of the distribution network.A simulation system was used to verify the pattern of changes in the voltage distribution of the line after the integration of distributed photovoltaic power sources.Thirdly,the research on voltage and reactive power optimization of power systems with photovoltaic power sources was carried out.Mathematical models for static and dynamic voltage and reactive power optimization are established,and particle swarm optimization is used to optimize the on-load voltage regulating transformer,reactive power compensation capacity,and reactive power capacity of photovoltaic grid-connected inverter.Numerical examples verify the effectiveness of the optimization results.Finally,a control strategy for participating in grid voltage adjustment when photovoltaic power is integrated into the distribution network was constructed to dynamically and continuously compensate for reactive power in the distribution network.Build a simulation model for the photovoltaic power generation grid connected system,and verify that this strategy can quickly adjust the reactive power output of the photovoltaic inverter during power fluctuations of the photovoltaic and load,and improve the voltage quality of the distribution network.