The invention relates to a method for controlling power generation of a VSM wind turbine. The wind turbine comprises a machine side converter, a line side converter, a DC link, and an electric storage device electrically connected to the DC link. The method comprises determining a first power control signal to the machine side converter, determining a second power control signal for controlling a desired output power of the line side converter based on a storage device voltage error, and a power production reference, and determining a charging current reference for controlling charging and discharging of the electric storage device based on a DC-link voltage error.

Multiphase generator-conversion systems are disclosed. The system includes a multiphase generator having one rotor and m+1 number of electromagnetically coupled stators, each stator having a plurality of phase legs. The system includes a converter having m+1 conversion lines, each conversion line connected to the plurality of phase legs of one of the m+1 stators. Each conversion line has a rectification module. At most m of the m+1 rectification modules has an active filtering converter. At least one of the m+1 rectification modules has a passive rectifier. At least one of the active filtering converters is configured to directly control its current to vary the magnetic flux of the stator to which it is connected and indirectly affect the magnetic flux of the rest of the stators through the electromagnetic coupling. Also disclosed are wind turbines that include generation conversion systems and methods of mitigating harmonics in multi-phase generator-conversion systems.

A bearing arrangement includes a shaft, at least one contact bearing and at least one non-contact bearing and a controller. The controller is configured to control a magnitude of a restoring force applied to the shaft by the non-contact bearing in accordance with a sensed parameter such that a stiffness of the shaft is modified such that one or more resonance frequencies of the shaft are moved away from one or more external forcing frequencies.

The application involves a stability evaluation method and system of direct-drive wind turbine generator, which belongs to the technical field of wind power generation. It solves the problems of poor stability of direct-drive wind turbine generator, low safety performance, failure to realize mutual cooperation between online stability evaluation and parameter adjustment in the existing technology. Firstly, the variation of direct-drive wind turbine generator terminal voltage, current, power and PLL angle of direct-drive wind turbine generator is measured, the terminal energy and the energy negative gradient of direct-drive wind turbine generator is calculated. Then, the system stability is assessed according to the value of energy negative gradient, the influence of the critical parameters on system stability is analyzed and the preliminary adjustment strategy is proposed. It realizes the mutual cooperation between stability level evaluation and parameter adjustment, and improves the working efficiency of the system.

An electric power conversion circuit includes: first and second input terminals; first and second output terminals; first and third switches connected to the first output terminal; second and fourth switches connected to the second output terminal; first through fourth diodes that are bridge-connected between the first and second switches; fifth through eighth diodes that are bridge-connected between the third and fourth switches; a first bootstrap circuit that is connected to control terminals of the second and fourth switches; and a second bootstrap circuit that is connected to control terminals of the first and third switches.

The present application provides a method and a system for controlling continuous high voltage ride-through and low voltage ride-through of a permanent magnet direct-driven wind turbine. The method includes: determining a transient time period during which the wind turbine is transitioned from a high voltage ride-through state to a low voltage ride-through state; controlling the wind turbine to provide, during the transient time period, a gradually increasing active current to the point of common coupling; and controlling the wind turbine to provide, during the transient time period, a reactive current to the point of common coupling according to an operation state of the wind turbine before the high voltage ride-through state.

The invention relates to a method for limiting structural loads in a wind turbine in situations where the power produced by the wind turbine is increased or decreased. The limitation of structural loads is achieved by restricting the power ramp rate, i.e. the rate of change of increases or decreases in produced power. The restriction is only invoked if a maximum change of the produced power or the corresponding internal power reference within a time window exceeds a given threshold.

A technique for providing electric power to an electric power utility grid includes driving an electric power alternator coupled to the grid with a spark-ignited or direct injection internal combustion engine; detecting a change in electrical loading of the alternator; in response to the change, adjusting parameters of the engine and/or generator to adjust power provided by the engine. In one further forms of this technique, the adjusting of parameters for the engine includes retarding spark timing and/or interrupting the spark ignition; reducing or retarding direct injection timing or fuel amount and/or interrupting the direct injection; and/or the adjusting of parameters for the generator including increasing the field of the alternator or adding an electrical load.

A method and system of subsynchronous oscillations and interactions damping integrated in in a rotor converter based on an adaptive state feedback controller with two spinning vectors, and a Kalman filter whose parameters are optimized by minimizing maximum sensitivity under a constraint of positive damping for a plurality of sensible scenarios is provided. The damping signal generated by the damping module is applied either to a power proportional integer controller or to a current proportional integer controller.

A control arrangement of a multiple-stator machine, comprising a frequency converter for each of the plurality of stators and a controller for each frequency converter, wherein a controller of a frequency converter is realized to generate control signals for that frequency converter on the basis of current values relating to that stator, and to generate a compensation current value for a further controller on the basis of the received current values in the event of an open-circuit fault in a frequency converter; to receive a compensation current value from a further controller; and to compute a voltage reference for a subsequent transform stage of the controller on the basis of the received current values is provided. The invention further describes a current control module of a frequency converter controller of such a multi-stator machine; a multi-stator machine; and a method of performing fault-tolerant control of a multi-stator machine.