Sma Solar Technology Ag

Sma Technologie Ag

Frank Greizer

Sven Bremicker

Matthias Victor

Joachim Ralf Laschinski

Bernd Engel

Torben Westphal

Guenther Cramer

Jens Friebe

Gerd Bettenwort

Wilfried Groote

Günther Cramer

Adrian Haering

Holger Becker

Andreas Falk

Markus Hopf

Oliver Prior

Henrik Wolf

Thorsten Dingel

Ralf Joachim Laschinski

Peter Simon

Stefan Buchhold

Burkhard Müller

Oliver Arend

Wolfgang Reichenbaecher

Andreas Jeppe

Heinz-Josef Romanski

Matthais Victor

Uwe Hübler

Dr-Ing Henrik Wolf

Adrian Häring

Wolfgang Reichenbächer

A protective device for a photovoltaic system includes at least one input for connection to a photovoltaic generator and at least one output for delivery of an electric power supplied from the photovoltaic generator. The protective device includes a detection device for a signal applied via the at least one output, and is configured to provide a low level-limited voltage at the at least one output if an applied signal does not meet a predetermined criteria, and is further configured to connect the at least one output with low resistance to the at least one input via a switching device if the applied signal meets the predetermined criteria.

Protective device for a photovoltaic system

The invention relates to a photovoltaic system for feeding three-phase current to a power grid that includes several monophase or three-phase photovoltaic inverters that can be connected to the power grid at the output end and are each fitted with a disconnecting device at the output end. The system includes several photovoltaic generators that are connected to the input end of the photovoltaic inverters. A central control and monitoring unit is connected between the photovoltaic inverters and the power grid. The control and monitoring unit has a grid monitoring device at the feeding point to the grid to measure one or more grid parameters. At least one communication link is provided between the individual photovoltaic inverters or the individual disconnecting devices and the connected central control and monitoring unit such that the connecting devices can disconnect the individual photovoltaic inverters from the power grid by means of a control instruction signal of the communication link. The central control and monitoring unit includes a load unbalance recognition component and a load unbalance regulation component, wherein the regulation includes limiting the power variation between the individual phases to a predetermined value.

Photovoltaic system for feeding three-phase current into a power grid

On an inverter () for converting an electric direct voltage, in particular of a photovoltaic direct voltage source into an alternating voltage with a direct voltage input with two terminals (DC+, DC&#x2212;) and one alternating voltage output with two terminals (ACAC) and with one bridge circuit including semiconductor switching elements (S-S), said bridge circuit comprising one first bridge branch (Z) including four switching elements (S-S) and one second bridge branch (Z) including two additional switching elements (SS) as well as a freewheeling circuit provided with additional diodes (DD), the efficiency is further increased without high frequency interferences and capacitive leakage currents having the possibility to occur on the generator side. This is achieved in that a respective one of the freewheeling diodes (DD) forms a freewheeling branch together with a respective one of the switching elements (SS) located in the first bridge branch (Z), said freewheeling branch carrying a freewheeling current in a condition decoupled from the direct voltage.

Inverter, more specifically for photovoltaic plants

A protection system configured to couple between a generator that has a number of partial strings and an inverter includes a control device, and a series-connection switching device configured to selectively connect the partial strings together in series. The system also includes a parallel-connection switching device configured to selectively connect the partial strings together in parallel, wherein the series-connection switching device is actuated by the control device such that it interrupts the series connection of the partial strings in case of a hazard, and the parallel-connection switching device is actuated by the control device such that it connects the partial strings together in parallel in case of a hazard.

Method for limiting the generator voltage of a photovoltaic installation in case of danger and photovoltaic installation

A method of converting a direct voltage generated by a decentralized power supply system into three-phase alternating voltage by means of a plurality of single-phase inverters (WR-WR), said alternating voltage being provided for supplying an electric mains, is intended to avoid inadmissible load unbalances using single-phase inverters. This is achieved in that, upon failure of one inverter (WR-WR), an asymmetrical power supply distribution is reduced by limiting the output of the other inverters. The method makes it possible to simplify three-phase voltage monitoring.

Method for converting direct voltage into three phase alternating voltage

The invention relates an inverter that may be set up as part of a power generation system for the connection of a number of substrings, which, using DC switches, can be connected to each other in series into a string and with the inverter. The inverter includes a bridge circuit to transform the power generated by the string comprising series-connected substrings into a grid-compatible AC voltage and to feed the power into a grid. The inverter also includes a ground fault detector arranged on the AC side of the bridge circuit for ground fault monitoring of the string. A controller connected to the ground fault detector controls the DC switches so that in case of a ground fault, a complete decoupling of the connection of the string from the bridge circuit and a separation of the string into potential-free substrings is performed. A method of operating such a power generation system is also described.

Inverter, power generation system and method of operating a power generation system

In an overvoltage protection apparatus before an inverter configured to feed electric energy from a DC voltage source into an AC power grid, the overvoltage protection apparatus includes a DC voltage input stage. The DC voltage input stage includes at least two current-carrying lines and an EMC filter including interference suppressing capacitors and interference suppressing inductors, and surge arrestors configured to divert overvoltages with respect to ground are connected to the current-carrying lines after the EMC filter, from a point of view of the DC voltage source.

Overvoltage protection for inverters that comprise an EMC filter at their input end

A method of connecting a photovoltaic device to an AC power grid through an inverter includes monitoring a DC voltage at an input of an inverter, and activating the inverter when the monitored DC voltage exceeds a first predetermined threshold. The method further includes synchronizing an output voltage of the inverter with a grid voltage, connecting an output of the inverter to the AC power grid upon synchronization if the monitored DC voltage exceeds second predetermined threshold, and deactivating the inverter if a detected power being fed through the inverter falls below a predetermined power threshold while maintaining the connection between the output of the inverter and the AC power grid. Lastly, the method includes disconnecting the output of the deactivated inverter from the grid if the monitored DC voltage falls below a third predetermined threshold. Further, an apparatus that performs such functionality is also provided.

Method of and apparatus for connecting a photovoltaic device to an AC power grid

A solar power plant includes at least one photovoltaic module for generating power to be fed in a multi-phase grid. At least one inverter is provided for converting a direct voltage generated by the at least one photovoltaic module into an alternating mains voltage. A mains transformer is coupled to receive the alternating mains voltage from the inverter. The inverter is coupled to a primary side of the mains transformer. A direct voltage source coupled between an output of the at least one inverter and an input of the mains transformer such that a potential of the at least one photovoltaic module is displaced and that a bias voltage is set which is different from zero volts.

Device and method for generating alternating current

A load breaker arrangement includes first and second input terminals, respectively, and first and second output terminals. The arrangement also includes two relays connected in series with one another, wherein the two relays are coupled between the second input terminal and the second output terminal, a semiconductor switch connected in parallel with one of the two relays, and a third relay coupled between the first input terminal and the first output terminal. A control circuit, in a load breaker mode, turns on the semiconductor switch while the two relays and the third relay are closed, then opens the one of the two relays in parallel with the semiconductor switch, then opens the semiconductor switch to break a current between the second input and second output terminals, and then opens the other of the two relays not in parallel with the semiconductor switch and opens the third relay.

Load breaker arrangement

An inverter has two input lines; an inverter bridge connected between the input lines and including at least one half-bridge having two normally conductive gate-controlled semiconductor switches; a controller which supplies control voltages to the gates of the semiconductor switches in an operative state of the inverter; and a DC voltage source for supplying an auxiliary control voltage to the gates of the semiconductor switches in an inoperative state of the inverter so as to hold the inverter bridge in a non-conductive state between the input lines. The DC voltage source has a charging unit connected between the input lines in series with a further normally conductive gate-controlled semiconductor switch, and charging a storage unit for electric charge, which is connected to the gate of the further semiconductor switch such that this switch becomes non-conductive, when the storage unit has been sufficiently charged for providing the auxiliary control voltage.

Inverter comprising normally conductive gate-controlled semiconductor switches

A solar power plant with a plurality of photovoltaic modules for generating a power to be fed in a multi-phase grid, several photovoltaic strings, which are allocated to different phases, being connected to a primary side of a mains transformer and at least one inverter for converting the direct voltage generated by the photovoltaic modules into an alternating mains voltage conforming to the grid being provided and said mains transformer being provided with a neutral conductor and with a grounded terminal, is intended to be improved in such a manner that the life of the photovoltaic modules, in particular in case of thin-film modules, is increased, allowing for high conversion efficiency of the inverters at low wiring costs. This is achieved in that an additional direct voltage source is inserted between the neutral conductor and ground in such a manner that the potential of the photovoltaic strings is displaced and that a bias voltage is set, which is different from zero volt.

Solar power plant

The subject matter of the invention is an inverter (), more specifically for use in a photovoltaic plant () with a direct voltage input (connection terminals) for connection to a generator () and an alternating voltage output (connection terminals) for feeding into an energy supply network () as well as with a DC-AC converter () with semiconductor switch elements () and an intermediate circuit (), at least one short-circuit switch element () being connected in parallel to the generator (), so that the voltage will not exceed a maximum voltage value neither at the connection terminals () of the generator () nor between the connection terminals () of the inverter. This is achieved in that the inverter () comprises, in the intermediate circuit (), a buffer capacitor () that is connected to the generator () through a protection diode () so that said buffer capacitor () will not be discharged upon actuation of the short-circuit switch element (), the generator () working according to a clock rate in the short-circuit mode of operation.

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Kaufungen, Germany

Frank Greizer