Coordinate control strategy of VSC-MTDC based on model predictive control

Abstract

The voltage-source converter based multi-terminal direct current (VSC-MTDC) transmission system is mainly applied in grid-connection and long-distance transmission of new energy power generation. New energy power generation has volatility and uncertainty. When using traditional droop control strategy,VSC will be overloaded due to uneven power distribution,protection malfunction will be caused by excessive DC voltage deviation,and oscillation will occur due to communication delay. Therefore,a coordinated control strategy based on model predictive control (MPC) is proposed in this paper. The strategy optimizes parameters according to system state and sends VSC power reference,eliminating the influence of droop coefficient,line resistance and system topology on power allocation. The robustness of MPC also improves the stability of the system in the case of communication delay. The four terminal VSC-MTDC model is built in Simulink,and different operating conditions are set for time-domain simulation. The simulation results show that the control strategy can quickly adjust the converter station power and control the DC voltage when the system is disturbed,and ensure the system stability when the communication delay occurs,so as to improve the adaptability of the power system to the fluctuation and uncertainty of new energy generation.

Keywords

• voltage-source converter based multi-terminal direct current (vsc-mtdc)
• voltage-sourced converter (vsc)
• power sharing
• dc voltage deviation suppression
• droop control
• model predictive control (mpc)