Abb Research Ltd.

Abb Ag

Abb Schweiz Ag

Antonio Coccia

Francisco Canales

Leonardo-Augusto Serpa

Sami Pettersson

Gerardo Escobar

Ngai-Man Ho

Mikko Paakkinen

Rodrigo Alonso Alvarez Valenzuela

Alexandre Oudalov

Toufann Chaudhuri

Adrian Vasile Timbus

Gerold Knapp

Philippe Stefanutti

Manfred Winkelnkemper

Steffen Bernet

Karsten Fink

Nicolas Hugo

Marcel Merk

Yales De-Novaes

Marc Pellerin

Fabiana Da Silveira Cavalcante

An exemplary method and apparatus for detecting islanding conditions of a distributed grid are disclosed, wherein transfer of power through a power electrical unit is controlled on the basis of a control reference. The apparatus includes a first stage and a second stage performing a respective portion of the method. The first stage injects a reactive component to the control reference, and, for at least one electrical quantity of the grid, determines a change in the quantity induced by the injected component, and determines, on the basis of the change in the electrical quantity, whether to move to the second stage of the method. The second stage, for at least one electrical quantity of the grid, determines a value of the electrical quantity, forms a positive feedback term using at the determined value adding a positive feedback term to the control reference, determines a change in an electrical quantity induced by the feedback term, and determines islanding condition on the basis of the change in the quantity induced by the feedback term.

Method and apparatus for detecting islanding conditions of a distributed grid

A method is disclosed for controlling single-phase DC/AC converters, along with a converter arrangement having at least two single-phase DC/AC converters. A controller is provided which can control the at least two single-phase DC/AC converters, and an isolation transformer, wherein outputs of the at least two single-phase DC/AC converters are cascade-connected with each other and an input of the isolation transformer. The controller is configured to control the at least two single-phase DC/AC converters to deliver power from their inputs to their outputs by turns.

Method for controlling single-phase DC/AC converters and converter arrangement

An exemplary method and arrangement for estimating the frequency and the positive sequence of a fundamental component of a measured three-phase voltage are disclosed (&#x3bd;). The method includes measuring the three-phase voltage (&#x3bd;), calculating estimates of a fundamental frequency voltage component ({circumflex over (&#x3bd;)}) and a difference ({circumflex over (&#x3c6;)}) between positive and negative sequence components of the fundamental frequency voltage from an error ({tilde over (&#x3bd;)}) between the measured three-phase voltage (&#x3bd;) and at least one of the calculated estimates of the fundamental frequency voltage component ({circumflex over (&#x3bd;)}) and from an estimate of the angular frequency ({circumflex over (&#x3c9;)}) of the fundamental frequency voltage component, wherein the estimate of the angular frequency ({circumflex over (&#x3c9;)}) of the fundamental frequency voltage component is calculated from at lest one of the estimated differences ({circumflex over (&#x3c6;)}) and from the error ({tilde over (&#x3bd;)}) between the measured three-phase voltage and at least one of the calculated estimates of the fundamental frequency voltage component.

Method and arrangement for estimating angular frequency

A converter circuit has a first resonant converter that is connected on the DC voltage side to a first energy storage circuit, and a transformer. A second resonant converter is connected on the AC voltage side to the secondary winding of the transformer and on the DC voltage side to a load converter, and a CLL resonant circuit is connected to the first resonant converter and to the primary winding of the transformer. The CLL resonant circuit has a resonant capacitance, a first resonant inductance and a second resonant inductance.

Converter circuit and unit and system comprising such converter circuit

A method of controlling the grid-side current of a single-phase grid-connected converter having an LCL filter connected between the output of the converter and the grid includes measuring a grid voltage and at least one signal in a group of signals consisting of a grid-side current, a converter-side current and a capacitor voltage, estimating the fundamental component of the grid voltage, forming a grid-side current reference, a converter-side current reference and a capacitor voltage reference for the grid-side current of the LCL filter, forming estimates for the non-measured signals in the group of signals, forming a grid-side current difference term, a converter-side current difference term and a capacitor voltage difference term, and controlling the output voltage of the converter based on the grid voltage, a formed injection term and a formed estimate of the harmonic distortion term to produce a grid side current corresponding to the current reference.

Control method for single-phase grid-connected LCL inverter

An exemplary non-isolated DC-DC converter for a solar power plant, can be adapted to connect to a full-bridge inverter. The converter includes positive and negative input terminals, and positive and negative output terminals. A plurality of switches, diodes, inductors and capacitors are connected in a circuit configuration to the input and output terminals. A control means is connected to the circuit for controlling the switching of a first, second, and third switch between an open and closed state.

Non-isolated DC-DC converter for solar power plant

A method and an arrangement are provided for balancing the switching transient behavior of parallel connected power semiconductor components. The method includes providing a switch signal to the parallel connected power semiconductor components for changing the state of the components, forming control signals for each of the parallel connected components from the switch signal, and determining, during the change of state of the power semiconductor component, the voltage induced to an inductance in the main current path of the component in each of the parallel connected components. The method also includes comparing each of the induced voltages with a predetermined threshold voltage, measuring time differences between the time instants at which the induced voltages crosses the threshold voltage, and modifying one or more of the control signals on the basis of the measured time differences in the respective following state change for balancing the switching transient behavior.

Current balancing of parallel connected semiconductor components

An AC/DC intermediate-circuit converter has a very wide AC input voltage range with a ZVS three-level DC/DC resonant converter with an LLC series-resonant circuit. Two intermediate-circuit capacitors are connected in series between DC intermediate-circuit connections with their common connection point forming a DC intermediate-circuit center connection (). The DC intermediate-circuit connections are connected to the DC connections of a rectifier whose AC input connections have an AC input voltage applied thereto. A range changeover switch is arranged between an AC input connection and the DC intermediate-circuit center connection. The range changeover switch is closed in a lower AC input voltage range, when the ZVS three-level DC/DC resonant converter is operated on the basis of a 'two-level operating mode' modulation strategy, such that the LLC series-resonant circuit has the full DC input voltage present between the DC intermediate-circuit connections applied to it. The range changeover switch is open in a central AC input voltage range when the ZVS three-level DC/DC resonant converter is operated on the basis of the 'two-level operating mode' modulation strategy. The range changeover switch is open in an upper AC input voltage range when the ZVS three-level DC/DC resonant converter is operated on the basis of a &#x201c;three-level operating mode&#x201d; modulation strategy, such that the LLC series-resonant circuit has only half the DC input voltage that is present between the DC intermediate-circuit connections applied to it.

AC/DC intermediate-circuit converter having a very wide AC input voltage range

A controller circuit is specified, having a step-up controller, a resonant converter connected downstream of the step-up controller on the output side, a transformer, a rectifier, which rectifier is connected to the secondary winding of the transformer on the input side, and a CLL resonant circuit connected to the resonant converter and to the primary winding of the transformer, which CLL resonant circuit has a resonance capacitance and a first and a second resonance inductance. In order to reduce the switching losses, the CLL resonant circuit is embodied as a 'T' circuit.

Growing community of inventors

Baden, Switzerland

Antonio Coccia