Abstract:
Ein Konverter zur Übertragung von elektrischer Energie zwischen einem Gleichspannungs- (DC-)system und einem Wechselspannungssystem, weist gleichspannungsseitig eine positive DC-Eingangsspannungsschiene (1) und eine negative DC-Eingangsspannungsschiene (2) und wechselspannungsseitig mindestens zwei Ausgangsphasenanschlüsse (a, b, c) auf. Dabei liegt für jeden der Ausgangsphasenanschlüsse (a, b, c) ein Phasenkonverter (10a, 10b, 10c) vor, welcher an einer ersten Seite an die positive DC-Eingangsspannungsschiene (1) und die negative DC-Eingangsspannungsschiene (2) und an einer zweiten Seite an diesen Ausgangsphasenanschluss (a; b; c) angeschlossen ist und als Hochsetz-Tiefsetzsteller ausgebildet ist. Der Konverter weist eine Regelung auf, welche dazu ausgebildet ist, im Betrieb des Konverters jeden der Phasenkonverter (10a, 10b, 10c), in Abhängigkeit eines Verhältnisses einer DC-Eingangsspannung zu Momentanwerten von an den Ausgangsphasenanschlüssen (a, b, c) zu erzeugenden Ausgangsphasenspannungen, zeitweise entweder als reinen Tiefsetzsteller oder als reinen Hochsetzsteller zu betreiben.
Abstract:
A method for controlling a three-phase electrical converter (12) comprises: selecting a three-phase optimized pulse pattern (20) from a table (22) of precomputed optimized pulse patterns based on a reference flux (ψ αβ,ref ); determining a two-component optimal flux {ψ* αβ ) from the optimized pulse pattern (20) and determine a one-component optimal third variable (ζ*); determining a two-component flux error from a difference of the optimal flux ( ψ* αβ ) and an estimated flux (ψ αβ ) estimated based on measurements in the electrical converter; determining a one-component third variable error from a difference of the optimal third variable (ζ*) and an estimated third variable (ζ); modifying the optimized pulse pattern (20) by time-shifting switching instants (28) of the optimized pulse pattern (20) such that a cost function depending on the time-shifts is minimized, wherein the cost function comprises a flux error term and a third variable error term, wherein the flux error term is based on a difference of the flux error and a flux correction function providing a flux correction based on the time-shifts and the third variable error term is based on a difference of the third variable error and a third variable correction function providing a third variable correction based on the time-shifts; and applying the modified optimized pulse pattern (26) to the electrical converter (12).
Abstract:
A power electronic unit which comprises a controller (60) and at least one half-bridge (100) with a first switching element (2) and with a second switching element (3) and has a phase current output (1) between the two switching elements, in which the first switching element and the second switching element can be switched in push-pull mode for a switching time at a clock frequency, and in which the controller sets the switching time and/or the clock frequency as a manipulated variable in order to provide a predefined amplitude, frequency and phase angle of the phase current at the phase current output (6) in a switching cycle, with the result that the amplitude, the frequency and the phase angle at the phase current output can be predicted for the switching cycle, the sign of the phase current is used as an observation variable and the determined switching time for the switching cycle depends on the direction of the predicted phase current.
Abstract:
The disclosure relates to a method for controlling a multilevel converter to balance voltages of submodule energy stores. This balancing (30) involves calculating (31) predicted final voltages of energy stores at the end of a time interval to follow and selecting (32) which submodule of a phase arm to insert or bypass during the time interval based on a comparison of the predicted final voltages of the energy stores. The predicted final voltages are updated (33) in accordance with any selection made of which submodule to insert or bypass during the time interval. A control device (11) and a computer program product are also disclosed. Voltage balancing according to a pre-programmed modulation scheme is possible by means of the disclosed method.
Abstract:
A VAR dispatch system. A central control system connected to a network is configured to receive data reflecting local variations in conditions on a power grid and to transmit system control commands over the network. A plurality of VAR dispatch devices are connected to the network and to the power grid. Each VAR dispatch device is configured to detect local variations in conditions on the power grid and to transmit the data reflecting such local variations to the central control system and to receive control commands from the central control system. Each VAR dispatch device is configured to store power and to output stored power to the power grid based on local variations in conditions on the power grid. Each VAR dispatch device is further configured to output stored power to the power grid when the VAR dispatch device receives system control commands from the central control system.
Abstract:
Die Erfindung betrifft eine Wechselrichterschaltung mit zwei Gleichspannungsanschlüssen (1, 2) und zwei Wechselspannungsanschlüssen (L1, N) sowie einer Drossel (L), deren eine Seite über ein erstes Schaltelement (S1) mit dem ersten Gleichspannungsanschluss (1) und deren andere Seite über ein zweites Schaltelement (S2) mit dem zweiten Gleichspannungsanschluss (2) verbunden ist, wobei des Weiteren die eine Seite der Drossel (L) über eine aus einer ersten Diode (Dl) und einem dritten Schaltelement (S3) gebildeten ersten Reihenschaltung und die andere Seite der Drossel (L) über eine aus einer zweiten Dioden (D2) und einem vierten Schaltelement (S4) gebildeten zweiten Reihenschaltung mit dem ersten Wechselspannungsanschluss (L1) verbunden ist.
Abstract:
A system includes a controller programmed to control an inverter to supply a power grid with a maximum amount AC electrical power while operating within an operating area that is pre-defined based on hardware limitations of the inverter. The system allows the inverter to operate with a variable low-DC voltage input into the inverter as opposed to a preset threshold DC voltage, thereby maximizing the amount of power the inverter supplies to a power grid. The inverter controller operates by prioritizing the reactive power output by the inverter over the active power output by the inverter so that the inverter is able to generate an output that meets the reactive power command from a utility and supplies the maximum amount of active power.