Single-star multilevel modular converter (MMC) structure-based hybrid power electronic transformer and control method thereof

Abstract

The invention discloses a single-star multilevel modular converter (MMC) structure-based hybrid power electronic transformer and a control method thereof. The hybrid power electronic transformer comprises a three-phase transformer, single-star MMCs, a three-phase full-bridge inverter, a DC bus, an LC filter and a contactor, wherein each phase single-star MMC is connected in parallel to a corresponding transformer primary winding coil via a primary contactor, outputs of three phase single-start MMCs are connected in parallel to a public DC bus, a DC input side of the three-phase full-bridge converter is connected to the public DC bus, and an AC output side of the three-phase full-bridge converter passes through the LC filter and then is connected in series to start connection of a secondarywinding of the three-phase transformer via a secondary contactor. By dynamic compensation on an output voltage of the power grid and reactive power current compensation on an output current, adjustment of electric energy quality of the power grid is achieved, the safety, the reliability and the economy of running of the power grid are guaranteed, and the hybrid power electronic transformer has certain creativeness, practicability and application value.

Description

technical field [0001] The invention belongs to the technical field of application of power electronic devices in power systems, and in particular relates to a hybrid power electronic transformer based on a single-star MMC structure and a control method. Background technique [0002] With the development and application of power electronic technology in power systems, power electronic transformers have received increasing attention due to their good power quality regulation capabilities. The continuous expansion of the power system network puts forward higher requirements for reactive power compensation equipment and voltage restoration equipment in the power grid. [0003] Due to the low voltage level and limited output power of the traditional power electronic transformer, the traditional transmission transformer cannot adjust the power quality of the grid. The existence of a large amount of reactive power not only occupies the capacity of the transmission transformer, but...

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Problems solved by technology

[0003] Due to the low voltage level and limited output power of the traditional power electronic transformer, the traditional transmission transformer cannot adjust the power quality of the grid. The existence of a large amount of reactive power not only occupies the capacity of the transmission transformer, but also increases the loss of electric energy during the transmission process.

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