DC circuit protection method applicable to AC-DC hybrid power distribution network

Abstract

The invention discloses a DC circuit protection method applicable to an AC-DC hybrid power distribution network. The DC circuit protection method comprises main protection, local back-up protection and remote back-up protection, wherein the main protection comprises current differential protection, overcurrent protection and unbalanced current protection, the local back-up protection comprises current direction protection and low voltage protection and is free from influence of a transition resistor, a protection range includes all length of a circuit, and the remote back-up protection comprises current direction protection, interpole voltage protection, unbalanced voltage protection and differential unbalanced voltage protection. In order to reduce an AC fault, particularly after single-phase grounding short circuit, a DC power grid runs abnormally due to AC protection rejecting to move, and the AC fault can be isolated by the remote back-up protection.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a DC line protection method suitable for an AC-DC hybrid distribution network. Background technique [0002] In the DC line, in order to protect the power electronic devices, the converter station generally has an overcurrent blocking function, which improves the quick action requirements for the protection of the DC line. Because the delay time of fault current traveling wave and fault voltage traveling wave generally does not exceed 1ms, which meets the requirement of quick action, the combination of traveling wave protection and voltage mutation protection is generally used as the main protection of the DC line. However, as the traveling wave protection of single-ended electrical quantity protection, there are problems that the setting value is not easy to determine, it is difficult to distinguish internal and external faults, and it is greatly a...

AI Technical Summary

Problems solved by technology

However, in the DC distribution network using modular multilevel converters (MMC), smoothing reactors and filter reactors are generally not provided, and the structure of the DC distribution network is diverse, and the size of the current-limiting reactor And the installation location is not uniform, and there is not necessarily a physical boundary at both ends of the DC line

Therefore, the protection scheme set by the physical boundary is not suitable for the AC-DC hybrid distribution network with MMC

[0003] In addition, most of the current line protection schemes used in DC distribution networks only consider the protection of this section of the line, less consideration is given to the coordination of the protected line with adjacent lines, and the impact of AC faults, and there is no clear division of protection areas

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