Woodward Kempen Gmbh

Kk Wind Solutions A/s

Woodward Seg Gmbh & Co. Kg

Convertertec Deutschland Gmbh

Stephan Engelhardt

Andrzej Geniusz

Jörg Kretschmann

Joerg Kretschmann

Dirk Volker Leiting

Holger Wrede

Jan Van Leyen

Lars Kock

Disclosed is a method for operating a three-phase inverter on a three-phase load. The three-phase inverter has a direct voltage intermediate circuit, at least one three-phase bridge circuit, and at least one control unit for controlling the bridge circuit. In the at least one bridge circuit, at least two power switches per phase are provided, which are connected in series parallel to the direct voltage intermediate circuit. Depending on predefined target voltage values of the three phases of the inverter, the power switches of each individual phase are actuated via the control unit such that a three-phase alternating voltage is generated on the three-phase load via switching operations of the power switches. Very good dynamic control behaviour can be achieved despite cost-effective dimensioning of the IGBT power switches of the three-phase bridge circuit.

Method for phase-separated overcurrent protection of a three-phase bridge circuit

Provided is an apparatus for delivering electrical power, in particular for delivering regeneratively produced electrical power, which has at least one converter and at least one filter for matching the delivery of power by the converter to a load impedance. Also provided is a method for operating the apparatus for delivering electrical power which allows improved monitoring of the functioning of the filters or mains filters and which uses means for determining at least one filter current in at least one filter, which means are designed in such a manner that said means make it possible to determine the at least one filter current during operation of the apparatus. Comparison means are provided and generate an error information signal using the desired value and actual value of the filter current and a predefinable error criterion.

High accuracy mains filter monitoring for a multi-phase power system

The invention relates to a method to control power output of a doubly-fed induction machine to a grid including the steps of measuring grid voltage and grid current in a three phase coordinate system, transforming grid voltage and grid current into a stator frame coordinate system, decomposing the grid voltage and grid current in the stator frame coordinate system in a positive sequence system and in a negative sequence system, calculating active and reactive power in the positive and negative sequence system, and controlling active and reactive power in the positive and negative sequence system. The object to provide a method to control power output of a doubly-fed induction machine which provides good dynamics and is able to allow fault-ride-through operations when unbalanced grid voltages occurs is solved in that active and reactive power in the positive and negative sequence system are used as independent state variables in a state controller, whereas the state controller generates manipulated values in the positive and negative sequence system separately which are subjected as manipulated state vectors to a state feedback in a stator frame coordinate system without further control loops before the manipulated vector resulting from state feedback is used to set the rotor voltage.

Direct power control with component separation

The invention relates to a device and method for controlling a double-fed asynchronous machine (), preferably for a power plant, in particular for a wind or water power plant. The device includes an indirect converter () which is connected on the rotor side to the double-fed asynchronous machine (). The indirect converter () includes a rotor-side converter () and a line-side converter (). At least one control element () is provided for controlling the indirect converter (). At least one software-based and/or hardware-based damping element () is provided which has changeable damping characteristics.

Device for controlling a double-fed asynchronous machine

The invention relates to a method for operating a wind energy plant having a double-fed asynchronous machine, at least one inverter and at least one control device, wherein electrical energy is at least partly supplied into a grid via the inverter, the inverter comprises per phase at least one power semi-conductor module with at least two transistor circuits and at least two free-wheeling diodes and the inverter by using the control device is actuated at least at times via a pulse width modulation (PWM). The object, namely of providing a generic method for operating a wind energy plant in which an improved power output is effected even in the low-noise rotational speed range of the rotors, is achieved in that, at frequencies of the current to be impressed by the inverter on the machine side of less than 10 Hz, preferably less than 6 Hz, the switching-on duration and/or the switching frequency of the transistor circuits and/or of the free-wheeling diodes of the inverter are altered via the control device by taking their thermal heating into account.

Method for operating a wind energy installation

In a method for the compensation of rotor torque oscillations upon the occurrence of mains asymmetries in relation to a double-fed asynchronous machine () it is provided that at least one respective currently prevailing machine parameter is measured and/or derived, the at least one machine parameter is respectively decomposed by calculation into a positive and a negative sequence system component and optionally a DC component, and for the positive sequence system component, the negative sequence system component and optionally for the DC component of the at least one machine parameter, there are respective separate control members for controlling an adjusting value, to which the respective components of the machine parameters are fed as input components and the output values of which are additively superposed. In that case the control members are so adapted for controlling the adjusting value in such a way that the torque oscillations are counteracted. Alternatively there is provided a control member to which the cross-product of the positive sequence system components and negative sequence system components as well as the cross-product of the negative sequence system components and positive sequence system components are fed as an input value, the control member being so adapted for controlling the adjusting value in such a way that second-order torque oscillations are counteracted.

Method of and apparatus for compensation of oscillation effects in the event of mains asymmetry in a double-fed asynchronous machine

A method for operating a wind turbine that includes a generator device for outputting electric energy to a network, the generator device having a stator, and a controller device for controlling the generator device. To ensure sufficient protection of the wind turbine even during network fluctuations, a network voltage is determined using a network model at least as a function of a stator voltage measured with a first measuring apparatus and a network power measured with a second measuring apparatus, and the determined network voltage and a predeterminable maximum phase angle present between the stator voltage and network voltage are used to determine the maximum effective power of the wind turbine that can be output, and the output effective power is regulated as a function of the determined maximum effective power that can be output and a target effective power predetermined by the control device.

Method for operating a wind turbine

A protection system for a doubly-fed induction machine; with a stator and a rotor. The stator of the doubly-fed induction machine is connected to a grid, and the rotor of the doubly-fed induction machine is connected to the grid via a converter. The converter includes a machine side converter, and a DC-link and a line side converter. The protection system also includes at least one crowbar, the crowbar being connected to the rotor, at least one DC-chopper provided in the DC-link, a converter controller, and a separate protection device for DC-chopper and the at least one crowbar.

Protection system of a doubly-fed induction machine

In a method and an apparatus for controlling the output or drawn active and reactive power of a double-fed asynchronous machine (), the maintenance of a maximum permissible current () of the machine&#x2014;without the use of a subordinate current controller&#x2014;is ensured by virtue of the fact that, during the operation of the double-fed asynchronous machine, a maximum permissible desired value for the active power () to be output or to be drawn and a maximum permissible desired value for the reactive power () to be output or to be drawn are calculated with the aid of a model of the asynchronous machine from the maximum permissible current (), preferably corrected at least using the actual value of the current to be limited of the machine, in such a way that the maximum permissible current () is not exceeded. The predetermined active and reactive power desired values are then limited to the calculated maximum permissible values.

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Sonsbeck, Germany

Stephan Engelhardt