A star chain statcom based on auxiliary power unit and its control method

Abstract

The invention discloses a star chain type STATCOM based on an auxiliary power unit and a control method of the star chain type STATCOM. The system comprises an auxiliary power unit and three LC seriesresonance circuits, wherein the auxiliary power unit comprises six power switch tubes, six diodes and two energy storage capacitors; the six power switch tubes are reversely connected to one diode inparallel to form six switch tube modules; every two of the six switch tube modules are connected in series to form three switch tube series circuits; middle points of the three switch tube series circuits are connected to an inductance end of a three-phase link respectively through one LC series resonance circuit; the two energy storage capacitors are connected in series to form a capacitor series circuit; the capacitor series circuit and the switch tube series circuit are connected in parallel; and the middle point of the capacitor series circuit is connected to the middle point of a three-phase star link. According to the star chain type STATCOM based on the auxiliary power unit and the control method, the unbalanced reactive compensation capability of the star chain type STATCOM and the power density of the device are improved.

Description

Technical field: [0001] The invention relates to high-voltage and high-power power electronic technology, in particular to a star chain STATCOM based on an auxiliary power unit and a control method thereof. Background technique: [0002] Chained STATCOM has been widely used in the field of power quality management of medium and high voltage distribution networks. It has the characteristics of modularization and easy expansion, and can be directly integrated into medium and high voltage power grids without transformers. The traditional chained STATCOM topology can be divided into star structure and delta structure. Under the same voltage level, the star structure can use fewer units, thereby greatly reducing the complexity of the system, but the unbalanced reactive power compensation capability of the structure very weak. [0003] Invention patents CN201510196420.6 and CN201310101371.4 disclose the method of using zero-sequence voltage injection to realize a small amount of ...

AI Technical Summary

Problems solved by technology

The traditional chained STATCOM topology can be divided into star structure and delta structure. Under the same voltage level, the star structure can use fewer units, thereby greatly reducing the complexity of the system, but the unbalanced reactive power compensation capability of the structure very weak

[0003] Invention patents CN201510196420.6 and CN201310101371.4 disclose the method of using zero-sequence voltage injection to realize a small amount of energy exchange between phases, but due to the constraints of hardware topology, the software method can only perform a small amount of unbalanced reactive power compensation, unbalanced reactive power limited ability to compensate

Invention patent CN201220674796.5 discloses a star-connected chained STATCOM device with unbalanced current compensation function. It uses a power frequency transformer to provide a zero-sequence current loop to realize energy exchange between phases, thereby achieving any unbalanced compensation. However, the structure The industrial frequency transformer is very bulky and does not use the power density of the device to increase

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