Research On The Control Of Inverter For Single-phase PV Grid-connected Power Generation

The exploitation and utilization of renewable energy has become the hot spot of currentworld development, solar as the most basic energy, with its ubiquity, inexhaustible and clean,has become the focus of various renewable energy in research. There are variety use patterns,among them, photovoltaic grid-connected power generation draws great internationalattention.This paper makes an overall explanation and research of single-phase grid-connected PVsystem, emphatically analyzes its parameter design and inverter control strategy, Mismatchingof input and output power happens under high-intensity illumination in grid-connectedphotovoltaic system, which will cause excessive voltage and capacitor damage of DC-bus,and finally induce the power loss of system. To solve this problem, the paper proposed aDC-bus voltage protection. The more details about author’s work are as follows:First, this paper described from different topology structures and operation principle ofgrid-connected PV systems. Photovoltaic cell technology, maximum power point trackingtechnology and inverter control technology were studied in the article.Second, after a detailed analysis of the working mechanism of photovoltaic cell,established its model. And discussed a variable step method that is based on perturbation andobservation maximum power point tracking. The validity of the photovoltaic cell model isproved through the simulation PSIM.Third, the main circuit and control circuit of the system were designed. The parametersin each part of the main circuit were analyzed and calculated. This thesis proposed three-loopcontrol, they are voltage control outer-loop, current inner-loop plus DC-bus protection loop,which will automatically coordinate the input power to match output power when the voltageof DC-bus capacitor is rising, to avoid the voltage overtop. Made a detailed analysis ofphase-locked loop technology of the system, modeling and simulation it in PSIM.Finally, the whole system are simulated through PSIM software, its validity is provedthrough the simulation waveforms.