Siemens Aktiengesellschaft

Siemens Energy Global Gmbh & Co. Kg

Guenter Ebner

Klaus Wuerflinger

Mike Dommaschk

Christian Blug

Marcus Zeller

Kai Trunk

Maxime Delzenne

Li Shang-Jaeger

An electrical converter has an alternating-voltage side with at least two alternating-voltage terminals and a direct-voltage side. At least two series connections connected in parallel and each forming a converter arm of the converter assigned to one of the alternating-voltage terminals. Circular currents can flow between the series connections. According to the method, a load value describing the thermal load of the converter is calculated based on: an active power current value that indicates the active power current component of a phase current flowing across one of the alternating-voltage terminals; a reactive power current value that indicates the reactive power current component of the phase current flowing across the alternating-voltage terminal; and a circular current value that indicates the magnitude of the circular current(s) flowing between the series connections. The converter is controlled while also taking into account this load value.

Electrical converter and method for operating an electrical converter

A method and a device provide protection for a multi-terminal HVDC grid against faults. The method includes measuring a DC displacement voltage having a polarity and a value, determining if a short circuit fault exists by comparing the DC displacement voltage with a threshold displacement voltage and identifying a fault type based on the polarity and the value of the DC displacement voltage. The disclosed device contains a converter having a positive pole and a negative pole, a DC-switch substation, a DC line connecting the converter and the DC-switch substation and a transient fault detector. The transient fault detector contains a positive voltage sensor sensing a positive transient voltage of the positive pole and a negative voltage sensor sensing a negative transient voltage of the negative pole and a control unit which is adapted to derive a DC displacement voltage from the positive and the negative transient voltages.

Transient protection for multi-terminal HVDC grid

Electric power is transferred between an AC voltage grid and a DC voltage grid in the high-voltage range. Phase modules have at least one common DC voltage connection and separate AC voltage connections. A phase module branch between the DC voltage connection and each AC voltage connection has a series circuit of two-pole sub-modules, each with an energy storage device and a power semiconductor circuit in parallel with the energy storage device. The power semiconductor circuit is driven to generate either the voltage drop across the energy storage device or else a zero voltage at the two sub-module connection terminals. A converter transformer has a primary side on an AC voltage grid and a secondary side connected to the AC voltage connections. Improved protection against overloading is provided by at least one surge arrester between the or one of the common DC voltage connections and the inverter neutral point.

Modular multi-stage inverter comprising surge arrester

Growing community of inventors

Henfenfeld, Germany

Guenter Ebner