Control method for suppressing commutation failure based on hybrid cascade direct current power transmission system

Abstract

The invention provides a control method for suppressing commutation failure based on a hybrid cascade direct current power transmission system. The invention discloses a topological structure of a hybrid cascade direct current transmission system. The topological structure comprises a sending end adopting an LCC, a receiving end VSC converter or an LCC series VSC structure; the control method comprises the following steps: acquiring receiving end operation parameters of the hybrid cascade direct-current power transmission system in real time; according to the operation parameters of the receiving end and a preset threshold value of safe operation, judging whether the receiving end is about to generate or has generated commutation failure: if not, controlling the receiving end to operate in a first operation mode; and if yes, controlling the receiving end to switch from the first operation mode to a second operation mode. According to the control method for suppressing the commutation failure based on the hybrid cascade direct-current power transmission system, the commutation failure is suppressed, and meanwhile, the change of the transmission power of the direct-current system is reduced to the greatest extent.

Description

technical field [0001] The invention relates to the technical field of flexible direct current transmission, in particular to a control method for suppressing commutation failure based on a hybrid cascaded direct current transmission system. Background technique [0002] High-voltage / ultra-high-voltage DC transmission is one of the transmission methods widely used in my country's west-to-east power transmission. Due to the mature thyristor technology, it has great advantages in terms of capacity and cost compared with fully-controlled devices such as IGBTs. Therefore, these DC Inverters are basically composed of thyristors. However, the conventional line commutation converter (LCC) composed of thyristors needs power support on the inverter side, which has the following defects: commutation failure is prone to occur when the AC voltage on the inverter side drops or the harmonic content increases: if the receiving end Multiple DC commutation failures in the grid at the same ti...

AI Technical Summary

Problems solved by technology

However, the conventional line commutation converter (LCC) composed of thyristors needs power support on the inverter side, which has the following defects: commutation failure is prone to occur when the AC voltage on the inverter side drops or the harmonic content increases: if the receiving end Multiple DC commutation failures in the grid at the same time will cause large fluctuations in the frequency of the grid at the receiving end; in addition, the LCC also consumes a large amount of reactive power during operation, which may easily lead to failures at the sending or receiving end when the DC operating conditions change or DC is blocked. Large fluctuations in terminal grid voltage

[0004] However, in the prior art, there is a lack of a control method based on hybrid cascaded DC transmission system to suppress commutation failure, so as to reduce the risk of DC commutation failure and shorten the time of DC commutation failure

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