Design And Research Of Multi-string Photovoltaic Grid Inverter

Multi-string photovoltaic(pv) grid inverter compared to the traditional inverter can achieve the optimal power output of each line, have a higher working efficiency. This paper use the MATLAB software as a research tool.Further study of the characteristics of photovoltaic cells, adopting reasonable control strategy of photovoltaic(pv) grid for multid-string photovoltaic(pv) grid inverter. IN this paper analyzes the control strategy, given the structure of the model, and established the physical design of the platform to verify this theory. The mainly work done by basically has the following several aspects:(1) Set up photovoltaic cells universal model, validation of photovoltaic cells in the light, temperature and other parameters on the influence of the output performance. Photovoltaic battery model is set up, the photovoltaic battery light intensity of different impact on the output performance of the battery pack.(2) The use of the mathematical models of photovoltaic cells, validation and the research of the traditional MPPT(Maximum Power Point Tracking) algorithm, an improved variable step size P&O method(Perturb & Observe).(3) To establish a mathematical model of the MPPT controller and inverter, the use of voltage outer ring, internal ring current double closed loop control strategy of inverter dc bus voltage and grid current control and simulation using Matlab simulation platform.(4) Design and build low-cost grid inverter with MPPT controller hardware platform, the inverter through theoretical analysis and the element parameters optimization, finally completed the construction of the experimental platform.(5) according to the experimental platform which is built of theory research for validation, proved the correctness of the theoretical research.