Abstract: Method for optimizing a maximum power point of a solar cell stack having modules, each including an MLSD unit, and an inverter. The MLSD unit shuts down the module when module voltage falls below a first voltage threshold, and switches it on, when a predefined second voltage threshold is exceeded. For optimal performance, the solar cell stack carries out: Defining, changing an electrical control parameter to a first wait value so that the second voltage threshold is exceeded exceeded; maintaining first wait value for a first time period so the modules are switched on by the MLSD units; changing electrical control parameter to a threshold value in a variation range and determining current-voltage curves for the modules in variation range; determining maximum stack power from current-voltage curves of the modules in the variation range; and predefining the determined maximum stack power as the maximum performance point.

Abstract: In a method for operating an inverter assembly and inverter assembly for carrying out the method, to reduce the risk of triggering a ground fault circuit interrupter, before feeding in the alternating voltage, the leakage capacitance to ground is determined at the DC input of each inverter, and which AC output is connected to which line of the supply network is determined, and, taking into consideration the leakage capacitance and a defined maximum leakage current and the connection situation at the AC output, the power units are asymmetrically modulated so that the amplitudes of the voltages at the AC outputs of the power units differ in size. The voltage with the greater amplitude comes about at the AC output of this power unit connected to the phase connection. The voltage with the lower amplitude comes about at the AC output of the power unit connected to the neutral conductor.

Abstract: To improve voltage balancing at the DC link capacitor voltages of a multi-level inverter with a split DC link a modulation signal with a modulation signal amplitude as even harmonic signal of the output voltage or output current of the inverter is calculated from an actual electric power difference of the actual electric powers at the DC link capacitors and is superimposed onto the setpoint value for setting an output voltage or output current of the inverter.

Abstract: In a method for operating an inverter assembly and inverter assembly for carrying out the method, to reduce the risk of triggering a ground fault circuit interrupter, before feeding in the alternating voltage, the leakage capacitance to ground is determined at the DC input of each inverter, and which AC output is connected to which line of the supply network is determined, and, taking into consideration the leakage capacitance and a defined maximum leakage current and the connection situation at the AC output, the power units are asymmetrically modulated so that the amplitudes of the voltages at the AC outputs of the power units differ in size. The voltage with the greater amplitude comes about at the AC output of this power unit connected to the phase connection. The voltage with the lower amplitude comes about at the AC output of the power unit connected to the neutral conductor.

Abstract: A method which is improved relative to the prior art for controlling electrical network variables in a feed network, in which the correlation between at least one feed variable measured at an input of the feed network and at least one network variable measured at an output of the feed network is described in a model-like manner using a model of the feed network. In the event of an incorrect description of the correlation, an adaptation of the model of the feed network is carried out, a feed variable target value for the at least one feed variable is determined from a predefined network variable target value for the at least one network variable using the model of the feed network, and the at least one feed variable is set to the determined feed variable target value by a current converter.

Abstract: To improve voltage balancing at the DC link capacitor voltages of a multi-level inverter with a split DC link a modulation signal with a modulation signal amplitude as even harmonic signal of the output voltage or output current of the inverter is calculated from an actual electric power difference of the actual electric powers at the DC link capacitors and is superimposed onto the setpoint value for setting an output voltage or output current of the inverter.

Abstract: In a method for operating an inverter for converting DC voltage into AC voltage, having at least one DC/DC step-up converter for converting a DC input voltage applied at the step-up converter DC input into an output voltage higher by a voltage stroke, an intermediate circuit, a DC/AC converter and an AC output for connection to a supply network and/or consumers, a voltage ripple is superimposed on the intermediate circuit voltage and in each step-up converter a switch is switched on/off with a specific switching frequency and a specific duty cycle, for measuring the output voltage of each step-up converter and the intermediate circuit voltage including the voltage ripple. A minimum voltage stroke of each step-up converter is dynamically calculated as a function of the respective measured step-up converter input voltage and the measured intermediate circuit voltage ripple, which minimizes the intermediate circuit voltage setpoint.

Abstract: In a method for operating an inverter for converting DC voltage into AC voltage, having at least one DC/DC step-up converter for converting a DC input voltage applied at the step-up converter DC input into an output voltage higher by a voltage stroke, an intermediate circuit, a DC/AC converter and an AC output for connection to a supply network and/or consumers, a voltage ripple is superimposed on the intermediate circuit voltage and in each step-up converter a switch is switched on/off with a specific switching frequency and a specific duty cycle, for measuring the output voltage of each step-up converter and the intermediate circuit voltage including the voltage ripple. A minimum voltage stroke of each step-up converter is dynamically calculated as a function of the respective measured step-up converter input voltage and the measured intermediate circuit voltage ripple, which minimizes the intermediate circuit voltage setpoint.