Modular multilevel converter impedance correction device design method and correction device

Abstract

The invention relates to a modular multilevel converter impedance correction device design method and an impedance correction device. The impedance correction device is connected to the alternating current network side of a modular multilevel converter, and according to the frequency requirement of converter impedance correction, each equipment parameter of the impedance correction device can be obtained through a specific design method. Capacitors and inductors are introduced to the alternating current side of a modular multilevel converter through a primary equipment means, so the alternating current impedance characteristic of the modular multilevel converter is directly and accurately improved, the problem that oscillation is difficult to accurately and effectively solve through a control means is solved, the impedance characteristic of the flexible direct current converter is guided by primary equipment, the adverse effect of a complex control system and long link delay thereof onthe impedance characteristic is reduced or weakened, and the operation stability of the system is improved.

Description

technical field [0001] The present invention relates to the technical field related to flexible direct current transmission, in particular to a design method of an impedance correction device for a modular multilevel converter, an impedance correction device, and a modular multilevel converter system using the impedance correction device. Background technique [0002] The flexible DC transmission technology based on the voltage source converter has been vigorously researched and applied in recent years because of its fast and flexible active and reactive power control, which can provide voltage support for the AC grid and has no commutation failure. Compared with the traditional two-level and three-level converter topologies, the modular multi-level converter topology adopts sub-module cascading, which is easier to achieve high voltage levels, reduces AC harmonics, and greatly improves the high-voltage flexible DC The feasibility of the power transmission project has promote...

AI Technical Summary

Problems solved by technology

Compared with the two-level voltage source converter, the modular multilevel converter topology has more complex internal dynamic behavior, so its oscillation stability problem and control are very complicated

In addition, the control system link delay of the modular multilevel converter in the project is long, which makes the control strategy for oscillation suppression for a certain frequency unable to adjust the output of the converter in a timely and accurate manner as expected, and thus cannot Accurately adjust the impedance of the converter at this frequency, and have an uncertain control effect on the impedance characteristics of other frequency bands

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