Abstract
Active power and DC voltage regulation is the key control challenge in a voltage source converter based multi-terminal high voltage direct current system (VSC-MTDC), particularly when integrating renewable energy sources. In such a system, the droop control may result in VSC overloading, leading to unequal power distribution and DC voltage instability following a major disturbance. To enhance the control performance, this paper presents an adaptive droop control technique based on the headroom of VSC (HR-ADC). The designed approach uses the headroom of rectifying and inverting converters to adaptively adjust values of droop coefficient, thereby avoiding converter overloading when significant power interruptions occur. The planned strategy is adopted for the rectifying and inverting converters. To validate its effectiveness, the HR-ADC is compared with the variable droop control using the four terminal ± 400 kV MTDC transmission system in PSCAD. Simulation results demonstrate that the designed HR-ADC is autonomous and resilient, ensuring stable system operation even during significant disturbances such as converter outage or fault conditions in the MTDC grids.