Based On The Photovoltaic (pv) Grid Inverter Software Phase-locked Loop Technology Research

As the worsening environmental pollution and the increasing depletion offossil resources, the development and utilization of renewable energy in theprocess of development of human history has become increasingly urgent. Themain form of using photovoltaic energy is to fed back the power of photovoltaicpower generation system into the state grid. As one of several phase-locked looptechnology, software PLL become the core of the part of PV Grid. Softwarephase-locked loop technology research has focused on the points being capturedover zero, and then adjust step in the software as well as using the virtualcoordinate transformation method for input voltage signal. As the former onehas more drawbacks than the latter one, so the latter one is the main method forus to study. The main content of this paper are:1. Modeling the solar cells through the POWER SYSTEM module inMATLAB, make a detailed analysis of the nonlinear characteristics of the solarcell and the several factors affecting the power generation efficiency of thesolar.2. Doing test using a variable load on solar cells to obtain the nonlinear characteristic of solar cell under a normal conditions.3. See the software PLL technology in the grid-connected inverter asresearch subject. To ensure that the current generated by the photovoltaic powergeneration system and the grid voltage of the same frequency、the same phaseunder the normal state, for this purpose, and after a detailed analysis of thephase-locked loop works, studied several common software phase-locked looptechnology based on the coordinate system transformation, and had acomparative analysis of them, and investigated the phase-locked ability ofseveral lock-in techniques through Matlab/Simulink under different conditions.4. Detailed elaboration of the software PLL system’s hardware designprocess which based on MSP430MCU, providing a software structure offlowcharts and experimental results.