Abstract: In a photovoltaic system including a plurality of strings, each includes a plurality of photovoltaic modules exclusively connected in series, bus lines to which the strings are connected in parallel, and a converter for feeding electric energy from the bus lines into a power grid. A system voltage drop between the bus lines can be adjusted by a controller of the converter, and a current sensor is provided for each string that at least determines whether a reverse current flows to the string and reports to the controller of the converter whether a reverse current flows to the string, and the controller of the converter reduces the system voltage present between the bus lines to stop the reverse current.

Abstract: A device for holding at least one switch within an enclosure includes a frame configured to surround at least a portion of the switch. The frame includes a bridge portion extending along a back portion of the switch, and lateral arms extending along respective side portions of the switch. The lateral arms include fastening equipment configured to provide an adjustable retention of the switch in the enclosure. The device may be included in a switch cabinet.

Abstract: An inverter for converting a direct current flowing between two input lines into an alternating current flowing between two output lines includes first and second series circuits each including two switches configured to switch at a high frequency and of an inductance connected between the switches, wherein the two inductances are magnetically coupled. The inverter further includes diodes which lead from opposite sides of the inductances to a first intermediate point and diodes leading from a second intermediate point to the opposite sides of the inductances, and an unfolding circuit which forwards a direct current flowing between the intermediate points and consisting of sine-shaped half-waves to the output lines with a polarity changing half-wave by half-wave.

Abstract: A device for converting direct voltage from an electrochemical store or a fuel cell to alternating voltage, includes a two-stage design having a single DC/DC converter stage for generating an intermediate circuit voltage from the output voltage of the electrochemical store or the fuel cell, which converter stage converts, in particular raises, the direct voltage in a wide input voltage range directly to an intermediate circuit voltage with which a DC/AC converter stage can be operated to generate the alternating voltage. The single DC/AC converter stage generates the alternating voltage from the intermediate circuit voltage. The invention further relates to a method for actuating a device for converting direct voltage from a store or energy generator into alternating voltage for feeding into a supply network.

Abstract: An electronic device is provided with a base as a first housing part and a cover as a second housing part, the first housing part and the second housing part being formed at least partially from conductive material. In an assembled state, the electronic device is electrically connected by a fastening pair respectively belonging to one of the two housing parts, the fastening pair having a pin with at least three pressure edges and a recess with an opening cross section adapted to the pin. In the assembled state, the pin protrudes into the recess in such a way that a holding force between the two housing parts is exerted between the pressure edges and the walls of the recess.

Abstract: The invention is a method and electric circuitry for measuring a grounding current of a photovoltaic power system incorporating a photovoltaic inverter, a measurement current being led through two shunts disposed at different points. The measurement current is a current that may flow alternatively at two different points at different electric potentials, the current flowing at a potential that differs by at least 50 V from the potential of the point of evaluation. The shunts are inserted in such a manner in a current mirror circuit that the voltage drop caused by the measurement in the shunts generates an asymmetry in the current mirror the magnitude of which is proportional to the measurement current. The measurement current is the grounding current of the photovoltaic power system with optional positive or negative pole grounding.

Abstract: A wiring testing device configured to test the wiring correctness of an inverter is disclosed. The inverter is configured to be connected to a low-voltage three-phase system with a neutral conductor serving as a reference point for grid-side conductor voltages. The wiring testing device includes a test circuit configured to measure the grid-side conductor voltages and determine an average value from the sum of the instantaneous values of the grid-side conductor voltages, and a display unit configured to display an error message if the average value exceeds a threshold voltage for a defined time period. The wiring testing device further includes a capacitor connected between a phase of the three-phase system and the neutral conductor configured to generate a voltage imbalance if the neutral conductor connection is missing, wherein the test circuit is configured to measure the conductor voltages and determine the voltage imbalance.

Abstract: 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.

Abstract: A DC/AC converter for converting DC power of a number of inductively connected generators into power grid conformal AC power for feeding into a connected power grid with a number of phases, includes an intermediate circuit with a positive and a negative intermediate circuit connection, and for each phase, a bridge. Each bridge includes a first switch between the positive intermediate circuit connection and a phase terminal, a second switch connected between a positive generator terminal of the generator and the phase terminal, a third switch connected between a negative generator terminal of the generator and the phase terminal, and a fourth switch between the negative intermediate circuit connection and the phase terminal.

Abstract: A power generation system for feeding power from generators into an AC grid, the system comprising a plurality of inverters connected to corresponding ones of the generators, and connected to the AC grid is disclosed. The plurality of inverters forms part of a data network, wherein one of the inverters forms a communication unit for receiving feed-in parameters from a grid control system and for controlling the plurality of inverters via the data network such that the power generation system feeds power to the AC grid in accordance with the feed-in parameters.

Abstract: In monitoring an isolation of an ungrounded power grid an AC voltage source is connected to the power grid via at least one test resistor. A test signal with a periodic continuous voltage course with regard to ground and with a frequency is applied to the power grid by means of the AC voltage source. A leakage current flowing due to the test signal is measured; and an ohmic isolation resistance is determined from the leakage current. The frequency of the test signal is varied such that an active current part of the leakage current keeps a predetermined recommended value at varying leakage capacitances of the power grid. This provides for a desired level of accuracy at maximum speed of isolation or ground fault detection.

Abstract: An insolation sensor is disclosed and is used to determine a solar light intensity as a basis for evaluating electric power generated by solar modules exposed to the solar light intensity. The insolation sensor includes an outer surface including a light entrance window, and at least one photo sensor configured to measure the solar light intensity. The at least one photo sensor is arranged behind the light entrance window. The insolation sensor further includes a detector device configured to detect precipitation and/or a resulting deposit on the surface which both affects the insolation sensor and the solar modules.

Abstract: 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.

Abstract: In an inverter includes two input lines for connection to a DC voltage source, two half-bridges connecting the two input lines, and two output lines for connection to an alternating current load or an AC power grid. Each half-bridge includes two pulse-operated switches with reverse connected diodes, each output line is connected to a center point of one of the half-bridges via an inductance, and the two output lines are connected to the same one of the input lines via a further pulse-operated switch behind the inductance with respect to the associated half-bridge.

Abstract: An inverter with galvanic separation including a resonant converter and an upstream mounted boost chopper is intended to provide galvanic separation in the context of a variable input and output voltage as it exists in photovoltaic systems, with the efficiency being intended to be optimized over the entire input voltage range. This is achieved in that a boost chopper or a buck chopper is mounted upstream of the resonant converter.

Abstract: The disclosure relates to a method for operating a DC-to-DC converter with two bridge arrangements with bridge switches, of which at least one is in the form of a switchable bridge arrangement which may be operated either as a full bridge or as a half bridge. The converter further includes a series resonant circuit, wherein the first and second bridge arrangements are coupled to one another via the series resonant circuit. At least one switchable bridge arrangement is operated as a full bridge in at least one time segment and as a half bridge in at least one further time segment within a half-period of a periodic switching of the bridge switches. The disclosure furthermore relates to a DC-to-DC converter and an inverter and a power generation installation including such a DC-to-DC converter.

Abstract: 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 (WR1-WR3), 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 (WR1-WR3), 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.