Abstract: The disclosure relates to a method for determining a characteristic curve for a photovoltaic (PV) string of a photovoltaic system having an inverter which is connected to the photovoltaic string and to a power supply network. The photovoltaic string includes a series connection of a plurality of photovoltaic modules, in which series connection at least one of the photovoltaic modules is integrated into the series connection of the photovoltaic modules via a DC/DC converter. The at least one DC/DC converter operates the photovoltaic module assigned thereto in a first operating mode M1 at a maximum power point by varying, over time, a conversion ratio of output voltage (UOut) to input voltage (UIn), and operates the photovoltaic module in a second operating mode M2 with a conversion ratio of output voltage (UOut) to input voltage (UIn) that is constant over time.

Abstract: The disclosure relates to a method for setting a power class of an inverter, wherein the inverter has a device type plate containing information about the inverter which is device-specific and independent of the selected power class, and wherein the inverter has a class plate which is selected from a plurality of power class-specific class plates each assigned to one power class from a plurality of power classes and contains information about the assigned power class. The method includes capturing an image of the device type plate and the class plate and reading out the device-specific information and the information about the assigned power class from the data captured as an image,—transferring a setting sequence to the inverter, wherein the setting sequence has the information about the assigned power class,—setting the power class of the inverter using the setting sequence following authentication of the read-out information. The disclosure also relates to an inverter having a power class that can be set.

Abstract: A fail-safe operating method for a decentralized power generation plant DG includes determining a leakage capacitance of a generator of the DG before connecting the DG. The method also includes comparing the determined leakage capacitance with a predetermined first limit value, and connecting the DG to a grid only if the determined leakage capacitance is smaller than the predetermined first limit value. A decentralized power generation plant is configured to perform the method.

Abstract: A fail-safe operating method for a decentralized power generation plant DG includes determining a leakage capacitance of a generator of the DG before connecting the DG. The method also includes comparing the determined leakage capacitance with a predetermined first limit value, and connecting the DG to a grid only if the determined leakage capacitance is smaller than the predetermined first limit value. A decentralized power generation plant is configured to perform the method.

Abstract: The disclosure relates to a method for determining a characteristic curve for a photovoltaic (PV) string of a photovoltaic system having an inverter which is connected to the photovoltaic string and to a power supply network. The photovoltaic string includes a series connection of a plurality of photovoltaic modules, in which series connection at least one of the photovoltaic modules is integrated into the series connection of the photovoltaic modules via a DC/DC converter. The at least one DC/DC converter operates the photovoltaic module assigned thereto in a first operating mode M1 at a maximum power point by varying, over time, a conversion ratio of output voltage (UOut) to input voltage (UIn), and operates the photovoltaic module in a second operating mode M2 with a conversion ratio of output voltage (UOut) to input voltage (UIn) that is constant over time.

Abstract: A fail-safe operating method for a decentralized power generation plant DG includes determining a leakage capacitance of a generator of the DG before connecting the DG. The method also includes comparing the determined leakage capacitance with a predetermined first limit value, and connecting the DG to a grid only if the determined leakage capacitance is smaller than the predetermined first limit value. A decentralized power generation plant is configured to perform the method.

Abstract: The disclosure relates to a method for detecting an arc in a DC circuit. The method includes measuring and analyzing an AC component (IAC) of a current (I) flowing in the circuit and determining at least one parameter of the AC component (IAC). The level of a DC component (IDC) of the current (I) is varied and a degree of correlation between the level of the DC component (IDC) of the current (I) flowing in the DC circuit and the at least one parameter of the AC component (IAC) is determined. An arc is detected and selectively signaled based on the degree of the determined correlation. The disclosure also relates to an apparatus for carrying out the method and to an inverter comprising such an apparatus.

Abstract: An inductor apparatus includes an inductor winding, a core defining a magnetic circuit for a magnetic flux generated by a current flowing through the inductor winding, at least one permanent magnet magnetically biasing the core by its permanent magnetization, and a magnetization device operable for adjusting a desired magnetization of the permanent magnet. The at least one permanent magnet is arranged within the magnetic circuit of the magnetic flux generated by the current flowing through the inductor winding. The magnetization device includes a magnetization winding and a circuitry configured to subject the magnetization winding to magnetization current pulses, thereby generating at a location of the permanent magnet a magnetic field which is able to change the permanent magnetization of the permanent magnet.

Abstract: A circuitry arrangement for a solar power plant includes a transformerless inverter for feeding electric power from at least one photovoltaic generator into an alternating power grid, a galvanic separation of all lines carrying current between the inverter and the power grid, and a DC voltage source in an offset path between one electric line at the input side of the galvanic separation and a reference potential. The DC voltage source provides an offset voltage. The offset path includes a DC branch and an AC branch connected in parallel. The direct voltage source is connected in series with a current sensor in the DC branch, and at least one capacitor is arranged in the AC branch. Further, a DC contactor triggered by the current sensor is arranged in the offset path.

Abstract: The disclosure relates to a method for detecting an arc in a DC circuit. The method includes measuring and analyzing an AC component (IAC) of a current (I) flowing in the circuit and determining at least one parameter of the AC component (IAC). The level of a DC component (IDC) of the current (I) is varied and a degree of correlation between the level of the DC component (IDC) of the current (I) flowing in the DC circuit and the at least one parameter of the AC component (IAC) is determined. An arc is detected and selectively signaled based on the degree of the determined correlation. The disclosure also relates to an apparatus for carrying out the method and to an inverter comprising such an apparatus.

Abstract: An inductor apparatus includes an inductor winding, a core defining a magnetic circuit for a magnetic flux generated by a current flowing through the inductor winding, at least one permanent magnet magnetically biasing the core by its permanent magnetization, and a magnetization device operable for adjusting a desired magnetization of the permanent magnet. The at least one permanent magnet is arranged within the magnetic circuit of the magnetic flux generated by the current flowing through the inductor winding. The magnetization device includes a magnetization winding and a circuitry configured to subject the magnetization winding to magnetization current pulses, thereby generating at a location of the permanent magnet a magnetic field which is able to change the permanent magnetization of the permanent magnet.

Abstract: The invention relates to a method and an apparatus for measuring the impedance of an energy supply system at a rated frequency by impressing a testing current (3) into the system and measuring (4) the resulting changes in a system current and a system voltage. According to the invention, the system current and the system voltage are measured during a first preselected time interval (T1) without impressing of the testing current and are measured during a second preselected time interval (T2) with the impressing of the testing current. The testing current is composed of at least one periodic signal with at least one testing frequency (f1, f2) that deviates from the rated frequency. Based on the measured system currents and system voltages, a Fourier analysis is used to determine a resulting impedance for the testing frequency (f1, f2). The impedance of the energy supply system at the rated frequency is derived from the impedance obtained for the testing frequency (f1, f2) (FIG. 1).

Abstract: The invention relates to a method and an apparatus for measuring the impedance of an energy supply system at a rated frequency by impressing a testing current (3) into the system and measuring (4) the resulting changes in a system current and a system voltage. According to the invention, the system current and the system voltage are measured during a first preselected time interval (T1) without impressing of the testing current and are measured during a second preselected time interval (T2) with the impressing of the testing current. The testing current is composed of at least one periodic signal with at least one testing frequency (f1, f2) that deviates from the rated frequency. Based on the measured system currents and system voltages, a Fourier analysis is used to determine a resulting impedance for the testing frequency (f1, f2). The impedance of the energy supply system at the rated frequency is derived from the impedance obtained for the testing frequency (f1, f2) (FIG. 1).