A kind of upfc controller and its control method based on observer and mmc

Abstract

The invention provides a UPFC (Unified Power Flow Controller) based on an observer and MMC as well as a control method thereof. The controller comprises an alternating current side power control module, three direct current side control modules, three reference voltage generation modules, a bridge arm circulation calculation module, a signal modulation module and an MMC submodule drive unit. Each direct current side control module is formed by a VS observer module, a circulation command generation module and a circulation control module; the control method concretely executes a corresponding function of each system module. According to the controller and the method provided by the invention, the process of data acquisition on a bottom layer module unit through a traditional method is removed, and the accurate estimation of bridge arm voltage can be quickly realized according to output voltage / current parameters and a bridge arm circulation value, so that data interchange between each direct current side control module and the bottom layer module unit is eliminated, and the real-time control frequency of the system is greatly improved.

Description

technical field [0001] The invention relates to a UPFC controller and a control method thereof, in particular to a control method of the UPFC controller based on an observer and MMC. Background technique [0002] The control system of UPFC is divided into two parts, the parallel part and the series part. The control goal of the parallel part is to make the UPFC generate DC voltage and keep it stable, while the series part is to realize the conversion from DC to AC, and its control goal is to make the UPFC Generate the required compensation voltage vector. [0003] Since German scholars proposed the Modular Multilevel Converter (MMC) topology in 2002, the converter has attracted a lot of attention from academic and industrial circles due to its low harmonic content, low switching frequency, and easy modular design. widespread attention. However, MMC also has certain defects. A large number of energy storage capacitors are continuously charged and discharged with the switchi...

AI Technical Summary

Problems solved by technology

Note that the bridge arm balance control needs to collect the voltage of all sub-module units and feed them back to the controller, which will make the data acquisition system complex and introduce a large amount of sampling value transmission delay to the real-time control of the system, especially when the sub-modules When the number of modules is large, the impact of this delay will greatly reduce the real-time control frequency of the system, and even affect the voltage balance of the sub-modules

Not only that, when MMC is extended to a higher level / power level, in order to meet the signal quantity requirements, the signal transmission system and control system often need to be redesigned, which undoubtedly increases the secondary design cost of the MMC-based UPFC system

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