Bifurcation Research And Control In Photovoltaic Power System

Faced of traditional energy consumption, photovoltaic (PV) power system plays a crucialcharacter in the new energy electricity generation because of its clean, non-polluting andrenewable advantages. However, it is the dispersibility, instability and discontinuity of solarenergy that make PV power system reliability low. It is easy to cause impact to power gridwhen PV power system connects to the power grid. Thus, it is indispensable to research thestability of PV power system. The paper discusses bifurcation phenomena in power electronicdevices of PV power system. Specific work is as follows:Firstly, this paper researches bifurcation phenomena in DC-DC boost converter of PVpower system, introduces the basic structure of PV power system and typical topology, andapplies engineering mathematical model of PV cells to simulate output characteristics. At thesame time, the second order discrete model of boost converter has been established, and theanalytical solution discretization method has been raised to study the bifurcation phenomenawhen reference current and input voltage change respectively. Then, the simulation model ofthe PV cell and boost converter have been set up to study how the temperature influencebifurcation in DC-DC boost converter.Secondly, this paper discusses the bifurcation research and control in inverter of PVpower system through theoretical derivation and simulation verification. The discrete modelhas been established and the first bifurcation point has been calculated through using thecharacteristics multiplier. Bifurcation has been analyzed by theory and computer simulation.Then, Time Delayed Feedback Control method is used to control bifurcation in inverter.Subsequent bifurcation point, the new one by controlled, has been calculated through usingthe eigenvalue of Jacobian matrix. The new bifurcation point has been analyzed by theory andcomputer simulation. At last, the simulation model of PV inverter has been set up andsimulation result shows that the stability of the system has been improved.