| With the increase of the large-scale centralized grid-connectedphotovoltaic system, in order to avoid the inherent intermittent anduncontrollable impact on the power grid, forecast of photovoltaic powergeneration became a new research hotspot in photovoltaic application. Inon-grid photovoltaic system and micro-grid system, effective predictionson power generation will improve the stability and reliability of thesystem; In addition to the PV plant investors effective power generationforecast will contribute to the analysis of the return on investment cycle,which is a reference to the investment.Energy storage devices (batteries, super capacitors, etc.) are keycomponents in the stand-alone PV systems. They are used to ensure thatthe system can work continuously when there is not adequate irradiationintensity; in addition, as the price of energy storage devices is high, thelarger capacity will lead to increased cost. The design of off-gridphotovoltaic system is a comprehensive consideration of stability,continuity and economic costs.In this paper, a method for the short-term forecast of the PV power generation is illustrated. The solar irradiance model, PV moduletemperature model and the solar cell/module model were set up. Withcloud cover and ambient temperature information from weather forecastwebsite, using LabVIEW software automatically prediction was realized.The predicted results and the measured values were compared. The resultshowed that the method is relatively simple with high accuracy. A modelof the stand-alone PV system was set up by the Trnsys software. With thismodel, the effect of battery capacity on the off-grid PV system underdifferent load-profiles was analyzed. This work can be guidance for theoff-grid system design, especially the choice of battery capacity. |
