Reliability model and algorithm research on HVDC system and flexible HVDC system

The main difference between flexible high-voltage direct current (HVDC) system and the traditional HVDC system is that there are two control degrees of freedom in the flexible HVDC system that is the amplitude and phase angle of the output voltage. While, there is only one control degrees of freedom in the traditional HVDC system which is the amplitude of the output voltage. Therefore, compared with the traditional HVDC system, there will not be the problem of commutation failure in the flexible HVDC system, and the control systems of the rectifier side and the inverter side being operated independently make the reliability of the system greatly improved. This article analyses and compares the main methods of reliability assessment. Analysing and comparing the reliability parameters of the two systems by using the state enumeration method, and using the economic characterisation to make the comparison more intuitive