Modularization multi-level converter model prediction control method

Abstract

The invention provides a modularization multi-level converter model prediction control method. The modularization multi-level converter model prediction control method includes the following steps: calculating a dq axis reference current according to a power command; conducting error correction on the dq axis reference current; calculating a cost equation through a phase current predicted value, and selecting the optimal phase voltage; calculating the cost equation through current predicted values inside bridge arms, and selecting the optimal compensation level; determining the number of submodules needing to be put into the bridge arms; calculating the cost equation according to a capacitor voltage predicted value of the submodules, determining the submodules put into the bridge arms; giving a trigger command that an upper switch tube is closed and a lower switch tube is opened to the submodules selected to be put in; giving a trigger command that the upper switch tube is opened and the lower switch tube is closed to the rest of the submodules. According to the modularization multi-level converter model prediction control method, the calculation amount of model prediction control in MMC control is reduced, the phase current control steady accuracy is improved through reference current correction, the overall structure is simple, and the modularization multi-level converter model prediction control method is more suitable for the characteristics of flexibility and expandability of an MMC.

Description

technical field [0001] The invention relates to a control method, in particular to a model predictive control method for a modular multilevel converter. Background technique [0002] Modular Multilevel Converter (MMC) adopts the cascade structure of modular design sub-modules, which has flexible and scalable characteristics. Compared with the traditional two-level voltage source converter, it has The advantages of good output characteristics, low harmonic content, no need for AC filters, and more suitable for occasions with high voltage levels are more and more used in VSC-HVDC systems. [0003] After searching the existing literature, it was found that an article titled "Modular Multilevel Converter Capacitor Voltage Balance Control Using Carrier Phase Shift Technology" was published in the "Chinese Journal of Electrical Engineering". The dual closed-loop control strategy similar to the VSC-HVDC system regulates the DC voltage and power, and introduces energy sharing contr...

AI Technical Summary

Problems solved by technology

However, when this method controls the MMC with N sub-modules in a single bridge arm, the number of switch combinations to be considered for each phase is . In the case of a large number of levels, the amount of calculation is huge, it is difficult to implement, and it lacks practicability

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