Analysis And Research Of Single-phase Photovoltaic Grid System

Energy is an important material foundation of the national economic development and human survival and development. In today’s energy shortage under the background of the times, the solar photovoltaic research has very important strategy sense. The single phase photovoltaic grid-connected generation system is researched in the paper. The system makes a profound analysis and research of photovoltaic maximum power point tracking (MPPT), grid-connected inverter and isolated island effect.The beginning of paper has made a profound interpretation of photovoltaic grid-connected power core component (inverter). The development, market, technology, defects and development foreground is undertook comparative study of its domestic and foreign product; and then from the components of photovoltaic power generation system to proceed, the important parts is introduced in detail in this paper; finally on the basis of photovoltaic grid-connected power topology describes the working principle of photovoltaic grid-connected generation system. Then, the core contents of this paper are led:(1) Photovoltaic maximum power point tracking (MPPT) is an important part of photovoltaic grid-connected generation system. Firstly, the principle of photovoltaic maximum power point tracking is analyzed; then the advantages and disadvantages of the common MPPT technology are analyzed in this paper, this paper using a more advanced method:improved perturbation and observation method--variable-step perturbation and observation method; finally using the Matlab/Simulink simulation to validate.(2) Grid-connected inverter is a core component of the photovoltaic grid-connected power system. Firstly, making a simple study and theoretical analysis for several grid current control strategy of single-phase grid-connected; and then using the SPWM control mode, and based on the improved, i.e. adding the grid voltage feed forward compensation device, which effectively reduces the grid voltage on net current influence; finally using the Matlab/Simulink simulation to validate.(3) In the light of isolated-island phenomenon appears in the photovoltaic grid-connected system. Firstly, analyzes some common detection method of isolated-island; and then according to the actual characteristics of the system, this paper uses the frequency difference of positive feedback isolated-island detection method, the working principle of the method is analyzed in detail; finally through the Matlab/Simulink simulation to validate the correctness of the method.(4) The control chip in this control system is a chip of DSP TMS320LF2407. Firstly, providing detailed analysis of all circuit hardware device selection and parameter design; then the main control unit of DSP and signal detection hardware device is designed; finally the control flow diagram and the software anti-interference measures of the system is designed.