The sub-module voltage-balanced control strategy of mmc-HVDC based on model prediction control

Abstract

The modular multilevel converter (MMC) has the advantages of high efficiency, low harmonic, modular design, and easy cascade, which has been widely used in the field of high voltage and large capacity energy conversion. In order to improve the dynamic response speed of the MMC-HVDC based on the modular multi-level converter, a novel method which combines a model predictive control (MPC) of MMC-HVDC system with improved sub-module voltage balanced control strategy is proposed. The method, which utilises the prediction model, feedback correction and rolling optimisation to obtain the optimal voltage control, overcomes the difficulties in the traditional way of setting PI parameters of the internal loop current controller and the outer loop controller and tackles the problem of low dynamic response. Finally, a 21-level MMC-HVDC system simulation model is built on PSCAD-EMTDC software platform. The simulation results indicate the effectiveness and feasibility of the control strategy.

Keywords

• dynamic response
• PI control
• predictive control
• voltage control
• power transmission control
• electric current control
• HVDC power convertors
• HVDC power transmission
• optimal control
• power conversion harmonics
• prediction model
• feedback correction
• rolling optimisation
• optimal voltage control
• internal loop current controller
• outer loop controller
• low dynamic response
• model prediction control
• modular multilevel converter
• low harmonic design
• modular design
• dynamic response speed
• model predictive control
• submodule voltage-balanced control strategy
• MMC-HVDC system simulation model
• large capacity energy conversion
• PI parameters
• PSCAD-EMTDC software platform