Vestas Wind Systems A/s

Tune Pedersen

Lars Helle

Duy Duc Doan

Ciprian Biris

Cem Özgür Gerçek

Gert Karmisholt Andersen

John Godsk Nielsen

Tusitha Abeyasekera

Søren Andersen

This disclosure proposes a topology that integrates a DC chopper into the Modular Multilevel Converter (MMC) cells of a power converter. The integrated DC chopper may include chopper resistors that may also be advantageously integrated into a heat sink for a power module including at least the power transistors of the MMC cell. Embodiments herein also describe a method for using an MMC cell's IGBTs and chopper resistors for providing a safe discharge of both cell capacitors and DC-link capacitors in different operating conditions.

DC chopper for MMC cell with integrated chopper resistor

A Direct Current (DC) chopper may be integrated into the Modular Multilevel Converter (MMC) cells of a power converter. The integrated DC chopper may include chopper resistors that may also be advantageously integrated into a heat sink for a power module including at least the power transistors of the MMC cell. The safe discharge of both cell capacitors and DC-link capacitors in different operating conditions is performed using Insulated-Gate Bipolar Transistors (IGBTs) and chopper resistors of an MMC cell.

A method, converter arrangement, and controller are disclosed for connecting an output of a converter with an electrical grid to control inrush currents into a grid filter assembly connected with the output of the converter, the electrical grid carrying an alternating current (AC) signal having one or more phases. The method includes determining a voltage of the AC signal and operating, after pre-charging a direct current (DC) link of the converter to a predetermined voltage, the converter using open-loop voltage control to produce an AC output signal that substantially matches the AC signal of the electrical grid. The open-loop voltage control is based on the determined voltage of the AC signal. The method further includes closing, after a predetermined amount of time of operating the converter using the open-loop voltage control, a switching device to thereby connect the output of the converter with the electrical grid.

Controlled inrush current for converter-connected grid filter

When performing interleaved switching, a power generation system may include chokes for filtering out a high-frequency ripple. However, because the chokes are interconnected, a common mode current can flow between the different parallel converters. Instead of connecting all the outputs of a parallel converter to the same choke, the same phase of each of the parallel converters is sent to one of the chokes. For example, the first phase signals are sent to a first choke, the second phase signals are sent to a second choke, and so forth. By doing so, air gaps in the chokes can be manipulated in order to provide a different inductance for the common mode current than a grid current. For example, the air gaps may be arranged such that the inductance corresponding to the common mode current is greater than the inductance corresponding to the grid current.

Choke for interleaved switching

Controlling operation of a wind turbine coupled to a power grid is disclosed. The power grid is monitored in order to determine whether or not there is a match between a demand for energy defined by power consumers connected to the power grid and supply of energy from power producers connected to the power grid. For instance, the price of energy may be monitored. In the case that the supply of energy from power producers exceeds the demand for energy, and a deficiency between the demand for energy and the supply of energy exceeds a first threshold value, the energy flow through the generator is reversed, thereby causing the generator to consume power received from the power grid. Thereby the deficiency can be reduced and the power grid can be stabilised.

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Hinnerup, Denmark

Tune Pedersen