US Patent No. 9,917,443

PHOTOVOLTAIC SYSTEM AND METHOD FOR OPERATING A PHOTOVOLTAIC SYSTEM FOR FEEDING ELECTRICAL POWER INTO A MEDIUM-VOLTAGE NETWORK


Patent No. 9,917,443
Issue Date March 13, 2018
Title Photovoltaic System And Method For Operating A Photovoltaic System For Feeding Electrical Power Into A Medium-voltage Network
Inventorship Andreas Falk, Kassel (DE)
Bernhard Beck, Volkbach-Dimbach (DE)
Aaron Philipp Gerdemann, Kassel (DE)
Frank Niebling, Kaufungen (DE)
Assignee SMA Solar Technology AG, Neubiberg (DE) Adensis GmbH, Dresden (DE)

Claim of US Patent No. 9,917,443

1. A method for operating a photovoltaic system for feeding a medium-voltage grid, wherein the photovoltaic system has a photovoltaic
generator comprising a plurality of photovoltaic modules connected in series, at least one inverter and at least one medium-voltage
transformer, and wherein the medium-voltage transformer is connected on the primary side directly to a low-voltage AC output
of the inverter, the inverter is connected to the photovoltaic generator via a DC input, and the inverter permits reverse
currents from the low-voltage AC output to the DC input, comprising:
determining whether there is insufficient generation of electric power by the photovoltaic modules for feeding to the medium-voltage
grid;

maintaining a connection between an AC side of the inverter and the medium-voltage grid via the medium-voltage transformer
when insufficient electric power generation is determined; and

maintaining a connection between a DC side of the inverter and the photovoltaic generator when insufficient electric power
generation is determined,

wherein a number of the plurality of photovoltaic modules connected in series within the photovoltaic generator is sufficiently
large so that a forward voltage of the plurality of series-connected photovoltaic modules is greater than a voltage set at
the DC input owing to the reverse currents.