Symmetrical monopole type flexible direct-current converter station

Abstract

The invention relates to the technical field of flexible direct-current power transmission. The invention discloses a symmetrical monopole type flexible direct current converter station. The station comprises a modular multilevel converter, a transformer and a grounding module. The input end of the transformer is connected with an alternating-current power grid; the output end of the transformer is connected with the input end of the modular multilevel converter, the neutral point of a valve side winding of the transformer is grounded through a grounding module, and the neutral point of a network side winding of the transformer selects a corresponding grounding mode according to the alternating current bus voltage of the back-to-back flexible direct current power transmission system; the grounding module comprises a large resistance unit and a large inductance unit which are connected in series. According to the symmetrical monopole type flexible direct-current converter station, optimized system design methods such as zero-sequence injection can be adopted, so that the equipment investment is reduced; and the number of used equipment is relatively small, the structure is simpler,and therefore the cost is reduced. In addition, the grounding effect of the symmetrical monopole type flexible direct-current converter station is good, and effective ground potential reference is provided for whole-station equipment.

Description

technical field [0001] The invention relates to the technical field of flexible direct current transmission, in particular to a symmetrical unipolar flexible direct current converter station. Background technique [0002] As a new generation of DC transmission technology, flexible DC transmission, compared with AC transmission and conventional DC transmission, can flexibly adjust the voltage of the AC system connected to it while transmitting energy, and has better controllability and operation mode With significant advantages such as flexibility, it is widely used in scenarios such as wind power grid connection, passive network power supply, and grid asynchronous interconnection. [0003] At present, the existing flexible DC converter stations are generally composed of converters and converter and transformer equipment. Among them, the flexible DC converter station mainly adopts the following two methods for grounding; the first method is: the neutral point of the valve si...

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Problems solved by technology

However, during the process of implementing the present invention, the inventor found that the prior art has at least the following technical problems: When the flexible DC converter station is grounded in the first way, although the grounding effect is good, it will cause the flexible DC converter station t

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