Sma Solar Technology Ag

Marcel Kratochvil

Holger Behrends

Markus Hopf

Rainer Schmitt

Alexander Unru

Sebastian Bieniek

Raimund Thiel

Andreas Falk

Gerd Bettenwort

Sybille Pape

Burkard Müller

Oliver Prior

Joachim Ralf Laschinski

Michael Viotto

Christopher Merz

Dirk Hermeling

Thorsten Buelo

Thomas Wegener

Ralf Juchem

Torsten Otto

Gary Orbita

Johannes Lang

Thorsten BÜLO

A power converter between an AC side and DC of the power converter is disclosed. The AC side is connected to an AC supply grid and the DC side is connected to a DC grid. The power converter includes a bridge circuit connected to the AC side of the power converter via AC switches and connected to the DC side of the power converter via circuit breakers, wherein a DC link circuit of the power converter is chargeable from the AC supply grid via an AC precharging circuit. The power converter has an insulation monitor to measure the insulation resistance of the DC side when the AC precharging circuit is connected to the DC link circuit. The disclosure also includes a related method.

Power converter for transferring power between an AC side and a DC side, and power supply method

A device for converting electrical power between a PV generator and an electrolyzer. The device has an inverter arranged between a first side thereof and a transformer, and an active rectifier is arranged between the transformer and a second side of the device, such that an AC side of the active rectifier and an AC side of the inverter are connected to one another via the transformer. The inverter is configured to convert a first DC voltage on the DC side of the inverter into a first AC voltage on the AC side of the inverter and the active rectifier is configured designed to convert a second AC voltage on the AC side of the active rectifier into a second DC voltage on the DC side of the active rectifier. The device has a controller configured to influence a power flow between the first side and the second side of the device from a connected PV generator to a connected electrolyzer by adjusting an AC/DC transformation ratio of the active rectifier between the second AC voltage and the second DC voltage.

Device and method for converting electrical energy

A method and related apparatus for extending a DC voltage range of a rectifier circuit for the supply, from an AC grid, of a DC load which is connected to a DC rectifier output of the rectifier circuit, wherein an AC rectifier input of the rectifier circuit is connected via a grid connection point to the AC grid, wherein the rectifier circuit includes an AC/DC converter having an AC input and a DC output, wherein the AC/DC converter includes a converter circuit having semiconductor switches and freewheeling diodes connected in an antiparallel arrangement thereto, wherein an inductance is connected between the AC input of the AC/DC converter and the grid connection point. The method includes setting a desired DC operating voltage Uon the DC output of the AC/DC converter or on the DC rectifier output, or both, by an actuation of semiconductor switches of the AC/DC converter, wherein, when the desired DC operating voltage Ulies below a value of an amplitude Ûof an alternating voltage on the AC input of the AC/DC converter, the semiconductor switches of the AC/DC converter are actuated for an exchange of reactive power Q(t) with the AC grid, which has a voltage-lowering effect upon the amplitude Ûof the AC voltage at the AC input of the AC/DC converter, such that the amplitude Ûapproaches the desired DC operating voltage U, and wherein the exchange of the reactive power Q(t) with the AC grid is executed during or shortly before an electrical connection or an electrical isolation of the DC load to or from the rectifier circuit.

Method for extending a voltage range of a rectifier, rectifier for carrying out the method, and electrolysis system

The disclosure relates to a method for operating an energy supply system, wherein a first and a second DC unit exchange power with an AC bus using a first and a second power converter. With transmission using a transformer, this power is combined and converted using a third power converter into a DC grid power of a DC grid and/or vice versa.

Method for operating an energy supply system, device for exchanging electrical power in an energy supply system, and energy supply system

The application describes a method for balancing voltages on a first and a second DC conductor in a DC grid using a balancing circuit with a first and second semiconductor switch connected in series between the first and second DC conductors, and a connection to a ground potential that is arranged between the first and second semiconductor switches. In the presence of an asymmetry in the voltages of the first and second DC conductors to ground potential, a compensation current is generated between at least one of the DC conductors ground potential via at least one of the semiconductor switches, with the asymmetry in the voltages being reduced by the compensation current (IA), with the voltages of the DC conductors to ground potential being balanced.

Method for balancing voltages in a DC grid and balancing unit for a DC grid

A method for detecting an arc in a circuit including a DC load, a DC source supplying the DC load, and a circuit arrangement between the DC source and the DC load is provided. A power flow between the DC source and an output of the circuit arrangement is cyclically interrupted by a switching circuit, such that the power flow is enabled in an active time window with the first period Δtand suppressed in an inactive time window with the second period Δt. Detection of a current I and/or a voltage U in two consecutive active time windows and comparison of the detected values of current I and/or voltage U of the active time window with the corresponding detected values from the preceding active time window can signal an arc if these values of the active time window differ from the corresponding values of the preceding active time window by more than a threshold value.

Method and circuit arrangement for detecting an arc, and photovoltaic (PV) inverter having a corresponding circuit arrangement

The disclosure describes a method for detecting an arc in a direct-current (DC) circuit comprising a DC load, a DC source supplying the DC load, and a circuit arrangement arranged between the DC source and the DC load. A power flow P between an input and an output of the circuit arrangement is suppressed by means of a switching circuit through cyclical interruption such that the power flow P is enabled in an active time window with the first period Δtand the power flow P is suppressed in an inactive time window with the second period Δt. Via detection of an input current Iflowing at the input and/or an input voltage Uapplied to the input and comparison of values of the input current Iand/or input voltage Udetected in the inactive time window with a current threshold value Ior a voltage threshold value Uan arc presence criterion is signaled if the input current Idetected in the inactive time window falls below the current threshold value Iand/or the input voltage Udetected in the inactive time window does not exceed the voltage threshold value U. The application also describes a circuit arrangement for detecting an arc and a photovoltaic (PV) inverter including such a circuit arrangement.

Method and circuit arrangement for detecting an arc and photovoltaic (PV) inverter having a corresponding circuit arrangement

A method of detecting a serial arc fault in a DC-power circuit includes injecting an RF-signal with a narrow band-width into the DC-power circuit and measuring a response signal related to the injected RF-signal in the DC-power circuit. The method further includes determining a time derivative of the response signal, analyzing the time derivative, and signaling an occurrence of a serial arc fault in the power circuit based on the results of the analysis. A system for detecting an arc fault is configured to perform a method as described before.

Method of and system for detecting a serial arc fault in a power circuit

A device for detecting alternating-current components iof an electric current iflowing in a direct-current circuit includes an inductor arranged in the direct-current circuit, and an AC path arranged electrically in parallel with the inductor, wherein the AC path comprises a series circuit made up of a capacitor and a primary winding of a transformer. The device further includes a voltage measuring device, wherein a secondary winding of the transformer is connected to the voltage measuring device via a low-pass filter circuit.

Apparatus for detecting AC components in a DC circuit and use of the apparatus

The disclosure relates to methods for sequentially disconnecting at least two electrical current sources from a common load or for sequentially connecting the current sources to a load, wherein the current sources are each connected to the common load via a switching unit, each comprising a parallel circuit comprising an electromechanically actuated switch and an associated semiconductor switch. In the two methods, first semiconductor switches are closed if they are still not closed and the relevant electromechanical switches are opened. In the method for sequential disconnection, then at least two of the semiconductor switches that were actuated or that were already closed are opened sequentially. In the method for sequential connection, a plurality of the semiconductor switches are first opened, of which then at least two are closed sequentially. The disclosure also relates to a photovoltaic system comprising an apparatus that is suitable for implementing the method.

Method for sequentially disconnecting/connecting electrical current sources from/to a common load

The apparatus for monitoring a photovoltaic system includes an incoupling circuit configured to couple an AC voltage test signal into the photovoltaic system, and an outcoupling circuit configured to outcouple a response signal, which is associated with the test signal, from the photovoltaic system, and an evaluation device, which is connected to the outcoupling circuit. The evaluation device is configured to identify events which adversely affect correct operation of the photovoltaic system. The apparatus is distinguished in that the outcoupling circuit includes a first transformer and a second transformer, each having a respective primary winding and each having a respective secondary winding which is connected to the evaluation device, with the primary windings of the first and second transformers being arranged in different electrical lines between a generator and an inverter in the photovoltaic system. The disclosure also relates to a corresponding method for monitoring a photovoltaic system.

Apparatus and method for monitoring a photovoltaic system

A device and corresponding method for monitoring a photovoltaic system to detect an occurrence of events impairing normal operation of the photovoltaic system is provide. The photovoltaic system includes a photovoltaic generator including a first group of photovoltaic modules and a second group of photovoltaic modules being different from the first group. The device includes a first and a second pair of coupling means, both pairs including signal coupling-in means for coupling a test signal into the photovoltaic generator, and a signal coupling-out means for coupling out a response signal from the photovoltaic generator, the first pair of coupling means configured to selectively detect the occurrence of the events in the first group of photovoltaic modules, and the second pair of coupling means configured to selectively detect the occurrence of the events in the second group of photovoltaic modules.

Device and method for monitoring a photovoltaic system

A method of detecting an arc fault in a power circuit includes injecting an AC-signal into the power circuit and measuring a response signal that is related to the injected AC-signal in the power circuit. The method further includes determining a frequency response of the power circuit from the response signal, analyzing the frequency response, and identifying a preferred frequency. A signal related to AC-current flowing in the power circuit within the preferred frequency range is measured and an occurrence of an arc fault in the power circuit is signaled depending on the measured signal. A system for detecting an arc fault is designed to perform a method as described before.

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Kassel, Germany

Marcel Kratochvil