Abstract: In a method for operating a power supply plant having a plurality of inverters and a plant controller connected to the inverters for communication, the power supply plant has a grid connection, which is connected to an AC voltage grid. Via the grid connection, the inverters exchange electrical interchange powers with the AC voltage grid such that the power supply plant exchanges a total interchange power, composed of the respective electrical interchange powers, with the AC voltage grid. By means of a respective regulator, the inverters adjust their respective interchange powers depending on a respective deviation of a voltage profile of a grid voltage from a respective reference profile with respect to a respective reference frequency and/or depending on a respective voltage amplitude differential between a respective grid voltage and a respective reference voltage.

Abstract: A method for regulating a decentralized energy generating system with a plurality of inverters (IN) is disclosed. The method includes receiving at the PPC a detected active power, reactive power and voltage amplitude at a grid connection point (PCC) of the energy generating system; and regulating, in a normal operating mode of the energy generating system, the reactive power and the active power to target values stipulated by a grid operator by virtue of the central control unit (PPC) dividing the stipulated target values into individual target stipulations for the plurality of inverters (IN) and communicating individual target stipulations to the inverters (IN). The method further includes selectively changing to a special operating mode of the energy generating system if particular criteria are present at the grid connection point (PCC) in a stipulated time interval.

Abstract: A method and associated apparatus for feeding electric power from a photovoltaic system via a grid connection point into an AC grid having a low short-circuit power is disclosed. The method includes connecting a DC voltage side of at least one first inverter of the photovoltaic system to a photovoltaic generator and an AC voltage side of the at least one first inverter to the grid connection point, wherein the at least one first inverter is operated as a current source, and connecting an AC voltage side of a second inverter of the photovoltaic system to the grid connection point, wherein the second inverter is operated as a voltage source based on measurement values of an AC voltage measured in the region of the photovoltaic system and a predefined characteristic curve.

Abstract: A method for regulating a decentralized energy generating system with a plurality of inverters (IN) is disclosed. The method includes receiving at the PPC a detected active power, reactive power and voltage amplitude at a grid connection point (PCC) of the energy generating system; and regulating, in a normal operating mode of the energy generating system, the reactive power and the active power to target values stipulated by a grid operator by virtue of the central control unit (PPC) dividing the stipulated target values into individual target stipulations for the plurality of inverters (IN) and communicating individual target stipulations to the inverters (IN). The method further includes selectively changing to a special operating mode of the energy generating system if particular criteria are present at the grid connection point (PCC) in a stipulated time interval.

Abstract: A method for regulating a decentralized energy generating system with a plurality of inverters (IN) is disclosed. The method includes receiving at the PPC a detected active power, reactive power and voltage amplitude at a grid connection point (PCC) of the energy generating system; and regulating, in a normal operating mode of the energy generating system, the reactive power and the active power to target values stipulated by a grid operator by virtue of the central control unit (PPC) dividing the stipulated target values into individual target stipulations for the plurality of inverters (IN) and communicating individual target stipulations to the inverters (IN). The method further includes selectively changing to a special operating mode of the energy generating system if particular criteria are present at the grid connection point (PCC) in a stipulated time interval.

Abstract: A method for regulating a decentralized energy generating system with a plurality of inverters (IN) is disclosed. The method includes receiving at the PPC a detected active power, reactive power and voltage amplitude at a grid connection point (PCC) of the energy generating system; and regulating, in a normal operating mode of the energy generating system, the reactive power and the active power to target values stipulated by a grid operator by virtue of the central control unit (PPC) dividing the stipulated target values into individual target stipulations for the plurality of inverters (IN) and communicating individual target stipulations to the inverters (IN). The method further includes selectively changing to a special operating mode of the energy generating system if particular criteria are present at the grid connection point (PCC) in a stipulated time interval.

Abstract: A method and associated apparatus for feeding electric power from a photovoltaic system via a grid connection point into an AC grid having a low short-circuit power is disclosed. The method includes connecting a DC voltage side of at least one first inverter of the photovoltaic system to a photovoltaic generator and an AC voltage side of the at least one first inverter to the grid connection point, wherein the at least one first inverter is operated as a current source, and connecting an AC voltage side of a second inverter of the photovoltaic system to the grid connection point, wherein the second inverter is operated as a voltage source based on measurement values of an AC voltage measured in the region of the photovoltaic system and a predefined characteristic curve.

Abstract: An inverter for converting DC power of a generator into grid-conforming AC power includes an inverter bridge circuit and a scanning circuit configured to trace at least one part of a characteristic curve of the generator to determine an MPP power value (PMPP). The scanning circuit is configured, in the case of a derating to a derated power (Pred), to trigger a tracing of the characteristic curve with provision of a first power profile deviating from the derated power (Pred) if an enable signal is present at the inverter, and to indicate a start and an end of the tracing by outputting a start signal and an end signal, respectively. The scanning circuit is further configured to provide a second power profile as AC power upon receiving a start signal, wherein the first power profile has a deviation from the derated power (Pred) with a sign that is opposite to a sign of a deviation of the second power profile from the derated power (Pred).

Abstract: For determining the topology of a grid section of an AC power grid, the grid section comprising a grid connection point, at least one branch branching off from the grid connection point and including a plurality of energy consumption and/or energy generation units, and at least one measurement point in the at least one branch, dependencies of variations of a grid voltage measured at the at least one measurement point based on variations of connection power values of at least some individual ones of the energy consumption and/or energy generation units are determined.

Abstract: A method and associated apparatus for operating a power station of fluctuating electrical capacity that, besides a voltage-setting system former outputting active power and reactive power and at least one load, is connected to a limited AC grid. The method and associated apparatus includes defining a desired self-contained operating range of the system former on the PQ level, in which operating range the system former is able to efficiently correct fluctuations arising in a mains voltage of the AC grid, ascertaining a present operating point of the system former on the PQ level, and controlling an output of active power and reactive power by the power station such that the operating point of the system former is kept in the desired operating range.

Abstract: In order to control a plurality of inverters, which are connected on their input side to a current source each and on their output side to a common grid connection point, electrical variables are measured at the individual inverters and are used for controlling the individual inverters, currents being output by the individual inverters depending on the electrical variables measured at the location of the individual inverters Effects of the connection equipment between the individual inverters and the common grid connection point on currents are determined, electrical variables being measured at the grid connection point and are set in relation to the electrical variables measured at the same time at the individual inverters. The connection equipment between the individual inverters and the common grid connection point is taken into consideration in controlling the individual inverters.

Abstract: In a method for black start of a power station including a plurality of inventers connectable to a local AC electrical grid, a first AC voltage is built up in the AC electrical grid by a first inverter, said first AC voltage being reduced in comparison with a rated voltage of the AC electrical grid by at least a quarter, and at least one second inverter is connected to the AC electrical grid after synchronization with the first AC voltage. After connection of the second converter, a second AC voltage, which is higher than the first AC voltage, is built up in the AC electrical grid.

Abstract: A method and associated apparatus for operating a power station of fluctuating electrical capacity that, besides a voltage-setting system former outputting active power and reactive power and at least one load, is connected to a limited AC grid. The method and associated apparatus includes defining a desired self-contained operating range of the system former on the PQ level, in which operating range the system former is able to efficiently correct fluctuations arising in a mains voltage of the AC grid, ascertaining a present operating point of the system former on the PQ level, and controlling an output of active power and reactive power by the power station such that the operating point of the system former is kept in the desired operating range.

Abstract: An inverter for converting DC power of a generator into grid-conforming AC power includes an inverter bridge circuit and a scanning circuit configured to trace at least one part of a characteristic curve of the generator to determine an MPP power value (PMPP). The scanning circuit is configured, in the case of a derating to a derated power (Pred), to trigger a tracing of the characteristic curve with provision of a first power profile deviating from the derated power (Pred) if an enable signal is present at the inverter, and to indicate a start and an end of the tracing by outputting a start signal and an end signal, respectively. The scanning circuit is further configured to provide a second power profile as AC power upon receiving a start signal, wherein the first power profile has a deviation from the derated power (Pred) with a sign that is opposite to a sign of a deviation of the second power profile from the derated power (Pred).

Abstract: In a method for black start of a power station including a plurality of inventers connectable to a local AC electrical grid, a first AC voltage is built up in the AC electrical grid by a first inverter, said first AC voltage being reduced in comparison with a rated voltage of the AC electrical grid by at least a quarter, and at least one second inverter is connected to the AC electrical grid after synchronization with the first AC voltage. After connection of the second converter, a second AC voltage, which is higher than the first AC voltage, is built up in the AC electrical grid.

Abstract: A method for grid support by means of an inverter is disclosed, wherein the grid is supported by feeding in compensation currents. The method includes measuring a prevailing grid state, and breaking down voltages measured for measuring the prevailing grid state into symmetrical components of the grid state including positive sequence system components and negative sequence system components. The method further includes determining symmetrical components of a compensation current including positive sequence system components and negative sequence system components of the compensation current as functions of deviations of the positive sequence system components and negative sequence system components of the grid state from reference values, and feeding-in a compensation current as the vector sum of the determined symmetrical components of the compensation current.

Abstract: For determining the topology of a grid section of an AC power grid, the grid section comprising a grid connection point, at least one branch branching off from the grid connection point and including a plurality of energy consumption and/or energy generation units, and at least one measurement point in the at least one branch, dependencies of variations of a grid voltage measured at the at least one measurement point based on variations of connection power values of at least some individual ones of the energy consumption and/or energy generation units are determined.

Abstract: To stabilize the grid voltage in a grid section which is connected to a higher-level grid via an apparatus having a variable voltage transformation ratio and which includes at least one energy consumption or generation unit, the voltage transformation ratio is changed in order to change a grid voltage level in the grid section. In at least in one mode of the method the grid voltage level is raised in order to counteract a rise in the grid voltage at the energy consumption or generation unit, or the grid voltage level is lowered in order to counteract a drop in the grid voltage at the energy consumption or generation unit. This is effectively possible since the power consumption or output of each energy consumption or generation unit in the grid section is controlled via a characteristic curve of the grid voltage present there.

Abstract: In order to control a plurality of inverters, which are connected on their input side to a current source each and on their output side to a common grid connection point, electrical variables are measured at the individual inverters and are used for controlling the individual inverters, currents being output by the individual inverters depending on the electrical variables measured at the location of the individual inverters Effects of the connection equipment between the individual inverters and the common grid connection point on currents are determined, electrical variables being measured at the grid connection point and are set in relation to the electrical variables measured at the same time at the individual inverters. The connection equipment between the individual inverters and the common grid connection point is taken into consideration in controlling the individual inverters.