US 11,656,256 B2
Method and photovoltaic inverter for determining the system capacity of a photovoltaic system to ground
Franz Fischereder, Pettenbach (AT); Andreas Luger, Pettenbach (AT); Christoph Pernegger, Pettenbach (AT); and Juergen Pirchenfellner, Pettenbach (AT)
Assigned to Fronius International GmbH, Pettenbach (AT)
Appl. No. 17/640,913
Filed by Fronius International GmbH, Pettenbach (AT)
PCT Filed Mar. 10, 2021, PCT No. PCT/EP2021/055970
§ 371(c)(1), (2) Date Mar. 7, 2022,
PCT Pub. No. WO2021/180754, PCT Pub. Date Sep. 16, 2021.
Claims priority of application No. 20162310 (EP), filed on Mar. 11, 2020.
Prior Publication US 2022/0334159 A1, Oct. 20, 2022
Int. Cl. G01R 27/26 (2006.01); G01R 31/12 (2020.01); G01R 15/04 (2006.01); H02S 40/32 (2014.01); H02S 40/38 (2014.01); H02J 7/35 (2006.01); H02J 3/38 (2006.01); H02M 3/04 (2006.01)
CPC G01R 27/2605 (2013.01) [G01R 15/04 (2013.01); G01R 31/12 (2013.01); H02J 3/381 (2013.01); H02J 7/35 (2013.01); H02M 3/04 (2013.01); H02S 40/32 (2014.12); H02S 40/38 (2014.12); H02J 2207/20 (2020.01); H02J 2300/24 (2020.01)] 15 Claims
OG exemplary drawing
 
10. A photovoltaic inverter (2) for determining the system capacitance (CPV) of a photovoltaic system (1) relative to ground (PE), the photovoltaic inverter comprising:
at least one DC input (3) for connecting to at least one photovoltaic module (4) or a string (4′) of a plurality of photovoltaic modules (4),
a DC/DC converter (5) with an input diode (DBoost),
an intermediate circuit (6),
a DC/AC converter (7),
an AC disconnector (8),
an AC output (9) for connection to a supply network (10) and/or consumer (11),
a control device (12), and
a measuring device (13) with a voltage divider (14), the measuring device comprising at least two resistors (R1, R2), a switch (Siso) for connecting a resistor (R1) of the voltage divider (14), and a voltage measuring unit (15) for recording measured voltages (UMi) on at least one resistor (R2) of the voltage divider (14) with the switch (Siso) of the voltage divider (14) open and closed, and for determining the system capacitance (CPV) from the temporal waveform of the recorded measured voltages (UMi),
wherein the voltage required for the measurement is provided by the intermediate circuit (6) in the form of the intermediate circuit voltage (UZK), and the measuring device (13) actuates an input short-circuit switch (SBoost) for short-circuiting the DC input (3) with the AC disconnector (8) open, as a result of which the intermediate circuit voltage (UZK) is applied to the DC input (3) in the reverse direction, and the measuring device (13) determines the system capacitance (CPV) from the temporal waveform of the measured voltage (UM2) after the switch (Siso) of the voltage divider (14) is closed.