Calculating method for short-circuit current on direct current side of MMC-MTDC (modular multi-level converter-based multi-terminal direct-current transmission system)

Abstract

The invention provides a calculating method for short-circuit current on the direct current side of an MMC-MTDC (modular multi-level converter-based multi-terminal direct-current transmission system). The calculating method comprises the steps of (1) calculating an MMC-MTDC direct-current network, and taking calculated steady-state operation current as a steady-state component of the short-circuit current; (2) performing equivalent conversion to obtain an equivalent passive circuit corresponding to an MMC; (3) calculating a fault component of the short-circuit current according to the MMC equivalent passive circuit, a direct-current power transmission line and a fault point direct-current voltage source equivalent calculating network; (4) adding the steady-state component and the fault component to obtain a final short-circuit current calculated result. Therefore, on the premise of guaranteeing the effectiveness, the efficiency for calculating the short-circuit current on the direct current side of the MMC-MTDC is obviously improved; due to the use of the method disclosed by the invention, the time for checking the requirement on the performance of a direct-current circuit breaker can be obviously shortened, so that the period for planning and designing the whole MMC-MTDC engineering is shortened; the calculating method has an important engineering practical value.

Description

technical field [0001] The invention belongs to the technical field of electric power system transmission, and in particular relates to a method for calculating the short-circuit current of an MMC-MTDC DC side. Background technique [0002] With the increasingly serious problem of energy shortage, the aggravation of environmental problems and the depletion of petrochemical resources, my country's demand for renewable resources has increased in recent years. Due to the particularity of renewable energy, it is necessary to consider adopting new technologies, equipment and grid structure to solve its grid connection problem. VSC-MTDC (multi-terminal flexible DC transmission system based on voltage source converter) is considered to be one of the most effective solutions. [0003] With the development of power electronics technology, MMC (Modular Multilevel Converter) based on fully controlled devices has greatly promoted the development of HVDC transmission technology. As a t...

AI Technical Summary

Problems solved by technology

However, it is not easy to build a detailed simulation model in time-domain simulation software, and it needs to consume a lot of time and computing hardware for subsequent simulation calculations

Considering that there are a variety of operating conditions in the actual project, and the short-circuit fault of the DC side may occur anywhere on the DC line, the detailed model based on the time-domain simulation software is not suitable for the calculation of the short-circuit current of the DC side

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