Method for determining a characteristic curve of a photovoltaic (PV) string, DC/DC converter, and photovoltaic system suitable for carrying out the method

• Main Authors: Schropp, Bernhard, Hopf, Markus, Viotto, Michael
• Format: Patent
• Language: English
• Published: 30.01.2024
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION; GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRA-REDRADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, E.G. USINGPHOTOVOLTAIC [PV] MODULES

The disclosure relates to a method for determining a characteristic curve for a photovoltaic (PV) string of a photovoltaic system having an inverter which is connected to the photovoltaic string and to a power supply network. The photovoltaic string includes a series connection of a plurality of photovoltaic modules, in which series connection at least one of the photovoltaic modules is integrated into the series connection of the photovoltaic modules via a DC/DC converter. The at least one DC/DC converter operates the photovoltaic module assigned thereto in a first operating mode M1 at a maximum power point by varying, over time, a conversion ratio of output voltage (UOut) to input voltage (UIn), and operates the photovoltaic module in a second operating mode M2 with a conversion ratio of output voltage (UOut) to input voltage (UIn) that is constant over time. The method includes operating the at least one DC/DC converter in the second operating mode M2 in response to a current signature for the current (IStr) through the photovoltaic string, determining the characteristic curve by varying the current IStr or the voltage UStr of the photovoltaic string by the inverter, and detecting values assigned to one another for current IStr and voltage UStr of the photovoltaic string in the second operating mode M2 of the DC/DC converter.