Method and device for controlling outage of converter station in multi-terminal flexible direct current transmission system

Abstract

An embodiment of the invention discloses a convertor station off-stream control method and device thereof for a multi-terminal flexible direct current transmission system. The multi-terminal flexible direct current transmission system comprises at least three convertor stations; the convertor stations are modularized multilevel converters; the DC (Direct Current) side of every single converter station comprises a DC current detector and at least a group of isolation switch blades and the AC (Alternating Current) side comprises a circuit inlet circuit breaker, a convertor transformer and a charging resistor which are in series connection mutually. The convertor station off-stream control method comprises switching converter valves in the converter transformers at converter stations which are required to be in off-stream to be in high-resistance states; detecting the DC side current of the converter stations which are required to be in off-stream; judging whether the DC side currents at the converter station stations which are required to be in off-stream are smaller than a preset value or not; disconnecting the isolation switch blades on the DC sides of the converter stations which are required to be in off-stream if the DC side currents at the converter stations which are required to be in off-stream are smaller than the preset value. The multi-terminal flexible direct current transmission system achieves the purpose that the operating converter stations are not influenced when partial converter stations in the multi-terminal flexible direct current transmission system is off-stream.

Description

technical field [0001] The invention relates to the technical field of direct current transmission, in particular to a method and device for controlling outage of a converter station of a multi-terminal flexible direct current transmission system. Background technique [0002] With the shortage of traditional energy sources, countries all over the world have turned their attention to the field of new energy sources, such as wind energy, solar energy, geothermal energy and small hydropower, and other new energy sources have been continuously developed and used. [0003] Due to its intermittency and uncertainty, there are great obstacles when new energy power generation is connected to the grid. Flexible DC transmission technology, especially the modular multi-level technology of the multi-terminal flexible DC transmission system, can be flexibly connected to multiple sites. New energy, through a large-capacity and long-distance power output channel, delivers power to load cen...

AI Technical Summary

Problems solved by technology

[0004] However, none of the multi-terminal flexible HVDC projects that have been put into commercial operation at present has the ability to shut down a single converter station or multiple converter stations at the same time. When the converter stations are out of service at the same time, it is necessary to shut down the entire multi-terminal flexible DC transmission system, disconnect the AC side circuit breakers of all converter stations, then isolate the DC side of the converter stations that need to be shut down, and then reconnect the remaining converter stations. The charging and unlocking are put into operation, which greatly limits the flexibility of the system operation, increases the outage probability of the entire multi-terminal flexible DC transmission system, and limits the application prospect of the system in the DC grid

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