Multi-target controller of three-level NPC based VSC-HVDC transmission system and Its RTDS simulation

This paper builds the dynamic mathematic model of the three-level Neutral Point Diode Clamped (NPC) converter, discusses the fundamental principles of the active and reactive power control for three-level Voltage Source Converter based HVDC (VSC-HVDC) system. To fully utilize the controllability of VSC-HVDC, multi-target controller is developed to control AC and DC system respectively. Improved sine wave PWM (ISPWM) technique is designed to raise the DC voltage utility rate. Real time digital simulation (RTDS) is done to verify the validity of the proposed control strategy and controllers and demonstrate the good performance of VSC-HVDC.