Single-phase Grid-connected PV Inverter MPPT Algorithm And Conrtol Strategy

With today’s energy shortages and importance of environmental protection, clean,renewable energy has become focus of the study. Solar energy is clean, safe, renewable,etc, so it has been paid more and more attention. Photovoltaic power generation is an effectiveway to make full use of solar energy, but it has the hortcomings of low energy efficiency andsystem instability. Thus, appropriate algorithms and strategies can improve the stability ofthe system itself and the utilization of solar energy, which became the focus of today’sgrid-connected PV one of the elements of the study.In this thesis, the object of study is a single-phase grid-connected PV which focuses onthe maximum power point tracking algorithm under the shadow and the DC bus overvoltagecontrol strategy. The main contents are as follows:Firstly, the thesis has elaborated the key technologies of grid-connected PV andthe problems. The different topologies of grid-connected PV and their advantages anddisadvantages have been compared, which is in order to determine the main circuit of thesystem model.Secondly, The working principle of the main circuit and determined the operatingparameters of the device by calculating have been analyzed. It has analyzed the workingprinciple and output characteristics of photovoltaic cells and the basic principle of themaximum power point tracking. On this basis, it has studied the output characteristics of thephotovoltaic cells and the maximum power point tracking algorithm under the shadow, whichhas established the simulation model in the PSIM, in order to verify the effectiveness of thealgorithm.Finally, taking into account the DC bus overvoltage problems when the light is too strongand the high frequency filtering effect of LCL filter, the master’s thesis has studied thetricyclic control strategy of DC bus protection ring, grid current loop and capacitor currentloop and designed the relevant parameters, in order to make the DC bus voltage control in thenormal range, while improving the quality of the current.It has established the simulationmodel for control strategies and validated the reasonableness of the control strategy.