Flexible direct current power grid modeling method suitable for fault current analysis

Abstract

Disclosed is a flexible direct current power grid modeling method suitable for fault current analysis; the flexible direct current power grid modeling method comprises the following steps of firstly,modeling a modular multilevel converter station by adopting an operator method to obtain input and output characteristics of the modular multi-level converter station; and establishing a flexible direct-current power grid model based on the MMC according to the input and output relation of the MMC converter station, and analyzing short-circuit fault current between the two poles of the flexible direct-current power grid. According to the method, the MMC converter station is recognized and modeled by adopting the operator method, complex analysis of dynamic characteristics in the converter station is omitted, and calculation is simple and convenient. The proposed fault current algorithm is suitable for different direct current power grid structures, and the modification amount is relativelysmall when the power grid structure changes; and meanwhile, the method is also suitable for multiple faults of the direct-current power grid, and has high universality.

Description

technical field [0001] The invention belongs to the technical field of power system fault analysis, and in particular relates to a modeling method of a flexible DC power grid suitable for fault current analysis. Background technique [0002] Due to the unbalanced distribution of energy in my country, long-distance and large-scale power transmission is required, and the flexible DC transmission system based on modular multi-level converter stations has a small footprint, fast dynamic response, no commutation failure, and can be independent The advantages of controlling active and reactive power are widely used in long-distance power transmission. [0003] Modular Multilevel Converter (MMC), as a new topology, still has a lot of problems to be solved in practical applications. The biggest problem is that the short-circuit current of the flexible DC transmission system is too large, and the existing DC circuit breaker cannot break it, so it is necessary to analyze the short-cir...

AI Technical Summary

Problems solved by technology

The biggest problem is that the short-circuit current of the flexible DC transmission system is too large, and the existing DC circuit breaker cannot break it, so it is necessary to analyze the short-circuit current

[0004] At present, the methods for analyzing the fault current of the flexible DC transmission system all adopt the static method, that is, the equivalent transformation of the fault circuit into a series-parallel circuit of capacitance, reactance and resistance, which does not take into account the dynamic process of the converter station, nor does it take into account the control of the converter station The role of the system in the failure process

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