Sending-end low voltage fault ride-through method for hybrid HVDC transmission system

Abstract

The invention relates to a sending-end low voltage fault ride-through method for a hybrid direct current power transmission system. When the AC voltage of a sending-end falls, the DC voltage of the sending-end is reduced and the direct current reference value is reduced; when the DC voltage of the sending-end is reduced so that a trigger angle achieves the set minimum trigger angle Alpha min, a receiving-end controls the direct current; if the DC voltage of the sending-end is reduced continuously, the receiving-end reduces the DC voltage until the receiving-end enters the set minimum current restriction region Imin, and then the receiving-end start waiting for restoration of a sending-end AC system; and when the sending-end AC system is restored, the sending-end controls the direct current and the receiving-end controls the DC voltage and the system restores normal operation. For the sending-end low voltage fault ride-through method, the receiving-end takes over the direct current control right when a fault occurs, and the current reference value can be adjusted according to the change of the DC voltage of the sending-end, so that the DC voltage of the receiving-end can be reduced and the DC cutoff can be prevented and the receiving-end power loss can be reduced.

Description

technical field [0001] The invention relates to a sending-end low-voltage fault ride-through method of a hybrid direct current transmission system, and belongs to the field of power electronics technology and direct current transmission. Background technique [0002] For the traditional DC transmission system, the commutation-based converter (LCC) based on the grid is often used. When the AC voltage is disturbed, the commutation failure at the receiving end is very easy to occur, causing serious stability problems to the AC-DC system. When the receiving ends of multiple DC transmission channels are connected to the same AC grid, if a certain DC channel fails to commutate, which intensifies the voltage fluctuation of the AC system, it may cause commutation failure to occur in other DC channels, which may lead to Systemic oscillations and even grid breakdown. In the prior art, a hybrid DC transmission system is often used. For a hybrid DC transmission system, when the AC volt...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art, and propose a low-voltage fault ride-through method at the sending end of a hybrid direct current transmission system, which solves the problem that the voltage at the sending end may be lower than that at the receiving end due to improper control of the receiving end in the hybrid direct current transmission system The problem of DC cut-off caused by terminal voltage

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