基于Boost电路单相两级式光伏并网发电系统的研究

传统上光伏并网发电大都采用工频或者高频变压器,但他们都有一些缺点。而非隔离型两级式光伏并网逆变器的应用可以尽可能地提高光伏并网系统的效率和降低成本,前级boost电路不仅能够提高最大功率跟踪(MPPT)的精度,而且又能使网侧逆变器较好的控制直流母线电压。后级逆变主要作用是实现对电网的跟踪控制确保逆变电路输出稳定、高质量的正弦变流电,因此采用电压外环、电流内环的双闭环控制。这种控制系统前级的最大功率点跟踪和后级的并网是互不干扰、相互独立的,不仅提高了系统控制可靠而且更有利于系统的模块化设计与集成。在Matlab/simulink建仿真模型,证明了该逆变系统的可行性并且达到了并网的要求。

Research on System Based on Boost Circuit in Single Phase Two-level Grid-connected Photovoltaic

Traditionally,power frequency or high-frequency transformers are used for most grid-connected generation,but they have some drawbacks. The application of non-isolated type two-stage photovoltaic grid-connected inverter can improve the efficiency of photovoltaic grid-connected system and reduce the cost as much as possible. The former boost chopper,not only can improve the accuracy of MPPT,and can also make the network side better control inverter DC bus voltage. The second level inverter＇s main function is to realize the tracking control of power grid,and ensure the stability and high quality of sine converter electricity. Therefore,double close loop control of outer voltage loop and inner current loop is used. The MPPT and the control of the grid-connected inverter are independent from each other. This not only improves the reliability of the control system,and is more conducive to modular design and integration. The simulation based on Matlab /Simulink proves the feasibility of the inverter system and it has reached the requirement of grid.