A method for suppressing commutation failure in HVDC transmission based on power bypass

Abstract

The present invention provides a method for suppressing commutation failure of HVDC power transmission based on power bypass, in which a power bypass device is connected in parallel at the outlet of the DC line on the inverter side in the HVDC power transmission system; the initial state of the parallel power bypass device is set ;Real-time monitoring and judging whether the DC voltage on the inverter side is zero; controlling the parallel power bypass device to close and blocking the inverter side converter; judging whether the AC system voltage on the inverter side is restored; controlling the parallel power bypass device to disconnect , to restore the operation of the HVDC transmission system. The method proposed by the present invention avoids the double-sided DC blocking caused by continuous commutation failure, improves the recovery speed of the system; avoids the DC switch breaking the DC current, saves a large number of power electronic devices, and improves the reliability and stability of the DC transmission system operation sex.

Description

technical field [0001] The invention relates to the field of DC transmission fault protection, in particular to a method for suppressing commutation failure of high-voltage DC transmission based on power bypass. Background technique [0002] With the gradual implementation of the "West-to-East Power Transmission" strategy, the UHV DC transmission project has been put into operation intensively, and my country has built the AC-DC hybrid power grid with the largest capacity and the most complex topology in the world. The continuous improvement of UHV DC single-circuit transmission capacity makes the characteristics of "strong DC and weak AC" appear, which are mainly reflected in: first, the receiving end power grid is mostly a load center, and multiple DC feed-in locations are concentrated, and the electrical distance between inverter stations is relatively short. Nearby, the failure of the AC system near the converter station may lead to multiple DC commutation failures at th...

AI Technical Summary

Problems solved by technology

The continuous improvement of UHV DC single-circuit transmission capacity makes the characteristics of "strong DC and weak AC" appear, which are mainly reflected in: first, the receiving end power grid is mostly a load center, and multiple DC feed-in locations are concentrated, and the electrical distance between inverter stations is relatively short. Nearby, the failure of the AC system near the converter station may lead to multiple DC commutation failures at the same time; the second is that the sending-end power grid is an energy-concentrated area, and the connection of the AC system is relatively weak. Interruption will cause some important sections of the power grid at the sending end to exceed the stability limit, some thermal power units will overspeed, and wind turbines will be disconnected from the grid due to low voltage or high voltage on a large scale, seriously threatening the safe and stable operation of the system

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