LCC-MMC (line commutated converter-modular multilevel converter) staggered and mixed bipolar direct current power transmission system

Abstract

The invention discloses an LCC-MMC (line commutated converter-modular multilevel converter) staggered and mixed bipolar direct current power transmission system. The system comprises a sending end convertor station and a receiving end convertor station, wherein an anode of the sending end convertor station comprises an LCC 1, a cathode of the sending end convertor station comprises an MMC 4; an anode of the receiving end convertor station comprises an MMC 3, and a cathode of the receiving end convertor station comprises an LCC 5; the anode of the sending end convertor station is connected with the anode of the receiving end convertor station through a direct current transmission line, and the cathode of the sending end convertor station is connected with the cathode of the receiving end convertor station through a direct current power transmission line. The floor space of the LCC-MMC staggered and mixed bipolar direct current power transmission system is smaller than that of a conventional direct current power transmission system based on a thyristor and that of a flexible direct current power transmission system completely based on the MMC, and the LCC-MMC staggered and mixed bipolar direct current power transmission system can be connected with a weak alternating current system and realizes decoupling control of active power and reactive power; an unilateral diode of a direct current line can prevent three-phase short circuit current from passing by the MMC when bipolar direct current short circuit fault occurs.

Description

technical field [0001] The invention belongs to the field of direct current power transmission, in particular to an LCC-MMC interleaved hybrid bipolar direct current power transmission system. Background technique [0002] With the rapid development of large-capacity power electronic devices, a large number of grid-connected new energy power generation, and the increasing demand for asynchronous interconnection between large regional grids, HVDC technology has ushered in a new development opportunity. At present, the development of DC transmission technology in China is divided into two directions: UHV DC transmission technology based on thyristors and flexible DC transmission technology based on turn-off devices. [0003] Thyristor-based UHVDC transmission system has mature technology and rich engineering experience. The Xiangjiaba-Shanghai UHVDC transmission project, Jinping-Sunan UHVDC transmission project, and Haminan-Zhengzhou UHVDC transmission project have been put in...

AI Technical Summary

Problems solved by technology

However, the flexible DC transmission system based on modular multilevel converters is composed of a large number of insulated gate bipolar transistors (IGBTs) and DC capacitors, and the cost is very high.

[0005] At present, hybrid DC power transmission systems based on thyristor bridges and modular multilevel converters have also been studied. The power transmission system still needs a large number of filtering and reactive power compensation devices on the side of the thyristor bridge, which cannot be connected to the weak AC system

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