Overvoltage computing method of modular multi-level converter

Abstract

The invention relates to an overvoltage computing method of a modular multi-level converter. An electromagnetic field theory is used in the method to compute converter stray parameters and build an overvoltage computing model, a circuit theory is used to compute overvoltage of converter electrical grids to the ground and between the electrical grids, the overvoltage is classified and analyzed based on metallic oxide arrester protection properties, and the method comprises the steps of extracting modular multi-level converter stray parameters, building a modular multi-level converter overvoltage model, and computing converter biggest overvoltage according to the arrester protection properties. By means of the overvoltage computing model, computing errors generated by assumed extraction of the stray parameters using equivalent capacitors or plate capacitors are avoided, overvoltage computing accuracy degree is improved, a protection level for direct protection of the modular multi-level converter arrester is confirmed, classification of modular multi-level converter overvoltage computing is simplified, overvoltage analysis difficulty and workload are lowered, device safety is ensured, and overvoltage analysis efficiency is improved.

Description

technical field [0001] The invention relates to the calculation of a high-voltage direct current transmission system, in particular to a method for calculating the overvoltage of a modular multilevel converter. Background technique [0002] Modular multilevel converter is a new type of converter based on turn-off devices. In the published "Mathematical Model of Modular Multilevel Voltage Source Converter" (Wang Shanshan et al. Mathematical Model of Modular Multilevel Voltage Source Converter. Chinese Journal of Electrical Engineering, Volume 31, Issue 24, 2011.) The development process and mathematical model of this modular multilevel converter are introduced in . Compared with the traditional line voltage commutated converter (Line Commutated Converter, LCC), it has the following characteristics: 1) The power electronic device is upgraded from a half-controlled device (such as a thyristor) to a fully-controlled device (such as a gate that can be turned off Thyristor (GTO)...

AI Technical Summary

Problems solved by technology

In order to complete the overvoltage analysis of the converter, the overvoltage analysis method needs to consider each component of the system where the converter is located, even multiple transmission systems, and the modeling workload is huge

At the same time, in order to investigate the maximum overvoltage that may occur in the converter, it is necessary to select a variety of fault conditions and operating modes based on experience, and conduct overvoltage analysis, comparison and judgment, which requires a huge amount of calculation and tedious tasks

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